Summary:
This re-implements sticky headers in JS to make it work on Android.
The only change that was needed was to expose a way to attach a an animated value to an event manually since we can't use the Animated wrapper and `Animated.event` to do it for us because this is implemented directly in the `ScrollView` component. Simply exposed `attachNativeEvent` that takes a ref, event name and event object mapping. This is what is used by `Animated.event`.
TODO:
- Need to check why momentum scrolling isn't triggering scroll events properly on Android.
- Remove native iOS implementation
- cleanup / fix flow
**Test plan**
Test the example list in UIExplorer, test the ListViewPaging example.
Closes https://github.com/facebook/react-native/pull/11315
Differential Revision: D4450278
Pulled By: sahrens
fbshipit-source-id: fec8da2cffce9807d74f8e518ebdefeb6a708667
