Cache UIManager constants in bridgeless new architecture on Android (Improve app start on low end/mid android by 150-300ms

[Szymon20000]

Summary:

This is what I noticed in many apps on the new arch. In paper architecture we created constants on UIManager thread so it didn't affect TTI however on the new arch it happens on js thread. This pr caches constants on first run (usually on onboarding and speeds up all subsequent runs.) The best solution would be to get rid of constants and just generate them at build time and put in hermes bytecode. I know that something like that is already on the roadmap but this seems to be a good temporary solution :)

Motivation: startup in bridgeless + new architecture was spending significant time in UIManager host functions (getConstants / getConstantsForViewManager) even on repeated launches.

This PR adds Android-side caching for UIManager constants and lazy view manager constants, preloads them early on app startup, and reuses them from UIConstantsProviderBinding to avoid recomputing on subsequent runs.

It also adds cache identity validation so stale cache is not reused after app/bundle changes (including OTA/file-bundle changes). Cache is only used when identity matches; otherwise it safely falls back to normal computation and refreshes cache.

Changelog:

[ANDROID] [CHANGED] - Cache and preload UIManager constants in bridgeless new architecture and invalidate cache when app/bundle identity changes.

Test Plan:

1. Build/install RNTester release on device:

   • ./gradlew :packages:rn-tester:android:app:installRelease
   • Result: BUILD SUCCESSFUL and Installed on 1 device.

2. Capture Hermes sampling profiles on release (two sequential launches, 10s window via react-native-release-profiler):

   • Launch/pull command used:
     • yarn workspace @react-native/tester react-native-release-profiler --fromDownload --raw --appId com.facebook.react.uiapp
   • Artifacts:
     • /Users/szymonkapala/work/react-native/.tmp/rntester-profiler-verify-20260312-214548/run1.cpuprofile.txt
     • /Users/szymonkapala/work/react-native/.tmp/rntester-profiler-verify-20260312-214548/run2.cpuprofile.txt

3. Profile comparison (sample-based):

   • Run 1 (expected cold): getConstantsForViewManager present (41 samples), getConstants present (1 sample).
   • Run 2 (expected cache hit): getConstantsForViewManager 0 samples, getConstants 0 samples.

This verifies first-run population + second-run reuse behavior with the new cache identity checks.

[javache]

Would it make sense to cache this in JS instead? We’d also want to have a feature flag for this.