Add imports_at_top rule

[udithaAnuranjana]

Summary

Adds a new opt-in imports_at_top style rule that requires file-scope imports to appear before other declarations.

This addresses #6892, where sorted_imports can sort import groups but does not report imports placed after other code.

Behavior

The rule:

• Allows regular and @testable imports at the beginning of a file.
• Allows leading conditional import groups using #if, #elseif, and #else.
• Supports nested conditional import groups.
• Reports imports that appear after another declaration.

Example violation:

import Foundation

struct Foo {}

import UIKit // violation

Leading conditional imports remain valid:

#if canImport(UIKit)
import UIKit
#endif

import Foundation

struct Foo {}

Implementation

• Adds ImportsAtTopRule as an opt-in SwiftSyntax style rule.
• Reports violations at the import keyword.
• Keeps the rule lint-only; autocorrection is not included.
• Updates existing SwiftLint plugin imports to comply with the new rule.
• Registers the rule and generated tests using make register.

Testing

• swift test --filter ImportsAtTopRuleGeneratedTests
• swift test

Full test suite: 1113 tests in 378 suites passed.

Closes #6892.

[SwiftLintBot]

	88 Warnings
⚠️	This PR introduced a violation in Aerial: /Aerial/Source/Models/Extensions/AVAsset+VideoOrientation.swift:60:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Alamofire: /Source/Features/MultipartFormData.swift:547:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Alamofire: /Tests/ConcurrencyTests.swift:794:18: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /iOS/DuckDuckGo/Subscription/Onboarding/Views/SubscriptionOnboardingCard.swift:145:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /iOS/DuckDuckGo/Fire/GranularFireConfirmationView.swift:196:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /iOS/DuckDuckGo/Fire/GranularFireConfirmationView.swift:197:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /iOS/DuckDuckGo/Fire/GranularFireConfirmationView.swift:198:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /iOS/DuckDuckGo/DaxEasterEggLogos/DaxEasterEggZoomTransitionAnimator.swift:29:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/SERPSettings/Tests/SERPSettingsTests/Mocks/MockSERPSettingsProvider.swift:121:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/Onboarding/Sources/Onboarding/SwiftUIExtensions/AnimatableTypingText.swift:25:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/Onboarding/Sources/Onboarding/SwiftUIExtensions/AnimatableTypingText.swift:26:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/Onboarding/Sources/Onboarding/SwiftUIExtensions/AnimatableTypingText.swift:27:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/LocalPackages/NetworkQualityMonitor/Sources/NetworkQualityMonitor/NetworkQualityView.swift:494:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/Preferences/View/PreferencesWebsitePermission/PreferencesWebsitePermissionsView.swift:162:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/Fire/View/FirePopoverViewController.swift:265:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/Fire/View/FirePopoverViewController.swift:266:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/DBP/DBPHomeViewController.swift:263:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/DBP/DBPHomeViewController.swift:264:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/DBP/DBPHomeViewController.swift:265:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/TabPreview/TabPreviewViewController.swift:233:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /macOS/DuckDuckGo/YoutubePlayer/Onboarding/DuckPlayerOnboardingModal/DuckPlayerOnboardingDecider.swift:57:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/BrowserServicesKit/Tests/DuckPlayerTests/DuckPlayerContingencyHandlerTests.swift:231:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in DuckDuckGo: /SharedPackages/BrowserServicesKit/Tests/DDGSyncTests/SyncConnectionControllerTests.swift:157:16: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Moya: /Package.swift:83:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in NetNewsWire: /Shared/Extensions/NSAttributedString+Extensions.swift:16:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in NetNewsWire: /Modules/RSCore/Sources/RSCore/RSScreen.swift:22:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in NetNewsWire: /Modules/RSCore/Sources/RSCore/RSImage.swift:20:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Utils/NimbleTimeInterval.swift:85:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeAKindOf.swift:31:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/SatisfyAnyOf.swift:96:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/HaveCount.swift:46:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/Match.swift:13:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/Matcher.swift:208:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/Equal.swift:263:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeLessThanOrEqual.swift:20:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/SatisfyAllOf.swift:96:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeLessThan.swift:20:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/AllPass.swift:67:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/AllPass.swift:68:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/AllPass.swift:69:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeGreaterThan.swift:20:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeGreaterThanOrEqualTo.swift:21:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/ContainElementSatisfying.swift:48:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/ContainElementSatisfying.swift:49:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/ContainElementSatisfying.swift:50:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeNil.swift:47:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/Matchers/BeIdenticalTo.swift:61:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/ExpectationMessage.swift:205:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/DSL.swift:117:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Nimble: /Sources/Nimble/DSL.swift:118:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/ExpandedCollectionViewController.swift:249:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/SinglePodcastViewController.swift:206:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/HorizontalCollectionListViewController.swift:42:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/SmallPagedListSummaryViewController.swift:305:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/DiscoverNetworksListViewController.swift:42:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/LargeListSummaryViewController.swift:273:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/SingleEpisodeViewController.swift:154:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/FeaturedSummaryViewController.swift:300:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/CategoryPodcastsViewController.swift:201:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/Categories/CategoriesSelectorViewController.swift:149:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in PocketCasts: /podcasts/CategorySummaryViewController.swift:100:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Tests/QuickLintTests/Result+CapturingAsync.swift:15:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Tests/QuickLintTests/Result+CapturingAsync.swift:16:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Plugins/LintError/LintError.swift:43:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Plugins/DefocusCommandPlugin/DefocusCommandPlugin.swift:45:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Plugins/LintCommandPlugin/LintCommandPlugin.swift:45:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Quick: /Plugins/LintWarning/LintWarning.swift:43:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Sourcery: /SourceryExecutable/main.swift:252:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Sourcery: /Plugins/SourceryCommandPlugin/SourceryCommandPlugin.swift:50:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/public/core/StringStorage.swift:189:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:32:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:33:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:34:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:35:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:36:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:37:10: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:133:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:135:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:137:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:139:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Swift: /stdlib/private/StdlibUnicodeUnittest/StdlibUnicodeUnittest.swift:76:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Wire: /WireMessaging/Sources/WireMessagingUI/Conversation/ConversationMessagesViewController.swift:161:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Wire: /wire-ios-data-model/Source/Utilis/ZMUpdateEvent.swift:27:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in Wire: /wire-ios-data-model/Support/Sourcery/generated/AutoMockable.manual.swift:321:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in WordPress: /WordPress/Classes/Utility/Analytics/ScreenTracking.swift:67:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in WordPress: /WordPress/Classes/Utility/Analytics/ScreenTracking.swift:83:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in WordPress: /Modules/Sources/WordPressUI/Views/AdaptiveTabBar.swift:361:1: Warning: Imports should appear at the beginning of the file (imports_at_top)
⚠️	This PR introduced a violation in WordPress: /Modules/Sources/WordPressKit/DeviceInformationProvider.swift:25:1: Warning: Imports should appear at the beginning of the file (imports_at_top)

	20 Messages
📖	Building this branch resulted in a binary size of 28796.74 KiB vs 28755.54 KiB when built on main (0% larger).
📖	Linting Aerial with this PR took 0.68 s vs 0.68 s on main (0% slower).
📖	Linting Alamofire with this PR took 0.97 s vs 0.97 s on main (0% slower).
📖	Linting Brave with this PR took 5.55 s vs 5.52 s on main (0% slower).
📖	Linting Brigade with this PR took 18.2 s vs 18.2 s on main (0% slower).
📖	Linting DuckDuckGo with this PR took 33.19 s vs 32.96 s on main (0% slower).
📖	Linting Firefox with this PR took 11.81 s vs 11.81 s on main (0% slower).
📖	Linting Kickstarter with this PR took 7.4 s vs 7.36 s on main (0% slower).
📖	Linting Moya with this PR took 0.38 s vs 0.38 s on main (0% slower).
📖	Linting NetNewsWire with this PR took 2.59 s vs 2.59 s on main (0% slower).
📖	Linting Nimble with this PR took 0.56 s vs 0.56 s on main (0% slower).
📖	Linting PocketCasts with this PR took 7.46 s vs 7.41 s on main (0% slower).
📖	Linting Quick with this PR took 0.36 s vs 0.36 s on main (0% slower).
📖	Linting Realm with this PR took 3.0 s vs 2.97 s on main (1% slower).
📖	Linting Sourcery with this PR took 1.61 s vs 1.64 s on main (1% faster).
📖	Linting Swift with this PR took 4.63 s vs 4.61 s on main (0% slower).
📖	Linting SwiftLintPerformanceTests with this PR took 0.18 s vs 0.18 s on main (0% slower).
📖	Linting VLC with this PR took 1.44 s vs 1.43 s on main (0% slower).
📖	Linting Wire with this PR took 16.56 s vs 16.57 s on main (0% faster).
📖	Linting WordPress with this PR took 10.65 s vs 10.67 s on main (0% faster).

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