191737 reset presubmit check

[ievdokdm]

Changed presubmit flow to immediately notify if any presubmit job failed and switch check-run back in progress if re-run all failed:

• Keep Dashboard Checks check-run always in progress unless presubmit successed
• Added Presubmit check-run
• Fail Presubmit check-run immediately once presubmit job failed
• Create new Presubmit check run if all jobs re-run

fix: flutter/flutter#191737

[gemini-code-assist]

Code Review

This pull request introduces a new 'Presubmit' check run flow that allows resetting failed check runs to in-progress when failed jobs are retried, along with refactoring several check-run handling methods and adding author tracking to presubmit jobs. The review feedback highlights several critical issues: a missing dart:io import in github_checks_util.dart causing a compilation error, potential null pointer exceptions in scheduler.dart due to unsafe null assertions on pullRequest and guard.checkSuiteId, an omitted GitHubCheckRunIdBuildTag in luci_build_service.dart for merge queues, and a grammatically incorrect getter name isSuccessed in presubmit_guard_conclusion.dart.

[eyebrowsoffire]

This looks good. I think in the longer-term, we should try to decouple the presubmit guard from the single GitHub checkrun ID and try to consolidate these checkruns so that we don't have three separate ones, but this works for now.