Generalize RTL Scroll Correction Logic (#38526)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38526

This changes the logic we use to correct scroll position on RTL ScrollView content change, to a new more generalized strategy of keeping a constant right-edge offset on layout change. This includes first layout, so that the initial scroll position is correct.

Changelog:
[Android][Fixed] - Generalize RTL Scroll Correction Logic

Reviewed By: yungsters

Differential Revision: D47627115

fbshipit-source-id: 33b2aae0cb603b7f7f2e2e6c127622fd531230e8