Summary:
1. We expose the `initialAppState` for Android in #19935, so we can remove the fallback check for Android.
2. Rename `RCTCurrentAppBackgroundState` to `RCTCurrentAppState`, it's a private file function, so it's safe to rename, `RCTCurrentAppState` is more suitable because we actually get app state, not app background state.
[Android] [Enhancement] - Remove android `initialAppState` fallback check.
Pull Request resolved: https://github.com/facebook/react-native/pull/23487
Differential Revision: D14121293
Pulled By: cpojer
fbshipit-source-id: fec196cef2969fe6f6f1571f4ebcafcec26266a1