feat: enable data filtering for batches

[jaissica12]

Background

• Kits that implement processBatch receive the full unfiltered batch from the SDK. Unlike individual events (which go through sendEventToForwarders with 5 types of data filtering), batches were forwarded without any filtering applied. This meant kits receiving batches could see events, user attributes, user identities, and event attributes that should have been blocked or stripped based on dashboard-configured filter rules.

What Has Changed

• Applied the same 5 data filters to sendBatchToForwarders that already exist in sendEventToForwarders: attribute forwarding rules, event name/type filters, event attribute filters, user identity filters, and user attribute filters
• Extracted shared filter helper functions (isBlockedByForwardingRule, isBlockedByEventFilter, filterEventAttributes, filterUserIdentities) from inline code in sendEventToForwarders so both event and batch paths reuse the same logic
• Added reverse-mapping functions in sdkToEventsApiConverter.ts (getMessageTypeFromEventType, getEventCategoryFromCustomEventType, getIdentityTypeFromBatchKey, getEventNameFromBatchEvent) to translate batch snake_case fields back to SDK numeric types needed by the filter functions
• If all events in a batch are filtered out, processBatch is skipped entirely for that forwarder

Screenshots/Video

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• {Any additional information or context relevant to this PR}

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes NA

[cursor]

PR Summary

Medium Risk
Changes the kit forwarding pipeline to filter and mutate processBatch payloads (events, attributes, identities) similarly to single-event forwarding, which could alter what downstream kits receive. Risk is moderate due to behavioral changes in core forwarding logic and new mapping/filter utilities.

Overview
Adds batch-level kit filtering so sendBatchToForwarders now removes blocked events and strips filtered event/user data (attribute forwarding rules, event name/type filters, event/screen attribute filters, and user identity/attribute filters), and skips calling processBatch when a batch is fully filtered out.

Refactors the single-event forwarder path to reuse new shared helpers in forwarder-utils.ts, adds reverse-mapping helpers in types.ts/sdkToEventsApiConverter.ts to interpret batch event payloads for filtering, and moves the SDK-wide extend implementation into utils.ts (updating call sites and tests accordingly).

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[cursor]

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[rmi22186]

Overall this is such a great improvement vs the mess that forwarders.js was prior. Great work not just migrating to TS, but cleaning and refactoring the logic to make it more understandable.

[sonarqubecloud]

Quality Gate failed

Failed conditions
31.0% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[mparticle-automation]

🎉 This PR is included in version 2.64.0 🎉

The release is available on:

• v2.64.0
• GitHub release

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