[expo-notifications][Android] map Expo and Firebase notifications correctly

[douglowder]

Why

Since #7280, some fields in Android notification content have been remapped. This is done in order to align the results seen in JS with the fields passed into the Expo push notification service when it sends notifications, and to align the API across the iOS and Android platforms.

However, this mapping is also happening when notifications are sent directly from Firebase. This leads to unexpected results where the data part of the notification payload does not appear correctly in the JS notification structures.

This PR fixes that by heuristically detecting whether a notification is sent from Expo or not, and performing the appropriate mapping in either case.

How

• Modified code in NotificationSerializer to detect when the body attribute is a JSON string (indicating that the notification was sent from Expo), and remapping the resulting bundles as appropriate for both cases.
• Modified NotificationsEmitter and mapNotificationResponse in the JS code to correctly unpack data strings in the case of Expo notifications.
• Added extensive debug logging, wrapped by BuildConfig.DEBUG so the logging does not happen in release/production builds.

Test Plan

• Both Firebase and Expo notifications should be mapped correctly in the test app
• Notification responses should be mapped correctly in both cases when tapping on a notification while the app is in background or not running
• CI should pass

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for npx expo prebuild & EAS Build (eg: updated a module plugin).

[linear]

ENG-12758 Investigate how Expo is remapping notification payload

[douglowder]

• [expo-notifications] useLastNotificationResponse should have only one effect #30653
• [expo-notifications][Android] map Expo and Firebase notifications correctly #30615 👈
• main

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[expo-bot]

The Pull Request introduced fingerprint changes against the base commit: e1ca69c

Fingerprint diff

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    "op": "changed",
    "source": {
      "type": "dir",
      "filePath": "../../packages/expo-notifications/android",
      "reasons": [
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      "hash": "a12805410193866c27ccf23179a53f3f7902e174"
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]

---

Generated by PR labeler 🤖

[douglowder]

Manual testing with the test app looks good:

• Notification data property appears the same whether originating from Expo or Firebase
• Notification responses appear correctly handled when app in background or killed
• Logging code working correctly when app built with BuildConfig.DEBUG

[wschurman]

If possible, don't special case for EAS Notify. Instead, special case for "JSON-like bodies".