Fix (Pointer|Touch)Events not firing after drag and scroll for Scroll…

…View and HorizontalScrollView

Summary:
Changelog: [Android][Fixed] - Fix such that when the scrollviews call `onChildStartedNativeGesture`, they appropriately call `onChildEndedNativeGesture` to unlock the native gesture such that `JSTouchDispatcher` or `JSPointerDispatcher` will continue to emit events.

### How did we find this issue?
As React Native is adding pointer event support for different input types, we noticed after pressing and dragging on a ScrollView, hover events would not fire.

### Why was this not an issue before?
This was always an issue -- it was just that `JSTouchDispatcher` worked its way around it by explicitly setting `mChildIsHandlingNativeGesture = false` on a `ACTION_DOWN` event, [code pointer](https://github.com/facebook/react-native/blob/main/ReactAndroid/src/main/java/com/facebook/react/uimanager/JSTouchDispatcher.java#L76). Similarly, `JSPointerDispatcher` [copied this logic](https://github.com/facebook/react-native/blob/main/ReactAndroid/src/main/java/com/facebook/react/uimanager/JSPointerDispatcher.java#L106).

With new hover support in `JSPointerDispatcher` no similar workaround was put in (or even a good place to insert).

### What's next?
* As a follow-up, we should look at removing this workaround (at least for `JSPointerDispatcher`)
* By searching for usages of where we `notifyNativeGestureStarted`, it looks like `ReactDrawerLayout` and `ReactSwipeRefreshLayout` both do and don't call the symmetric `notifyNativeGestureEnded`. This will likely be an issue in the future (or maybe if we remove the workaround)

Reviewed By: mdvacca

Differential Revision: D37977982

fbshipit-source-id: 0d18767f4debbf24cfb24b54df1310f6f96a0d03

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollView.java

@@ -532,6 +532,7 @@ public boolean onTouchEvent(MotionEvent ev) {
       float velocityX = mVelocityHelper.getXVelocity();
       float velocityY = mVelocityHelper.getYVelocity();
       ReactScrollViewHelper.emitScrollEndDragEvent(this, velocityX, velocityY);
+      NativeGestureUtil.notifyNativeGestureEnded(this, ev);
       mDragging = false;
       // After the touch finishes, we may need to do some scrolling afterwards either as a result
       // of a fling or because we need to page align the content

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java

@@ -404,6 +404,7 @@ public boolean onTouchEvent(MotionEvent ev) {
       float velocityX = mVelocityHelper.getXVelocity();
       float velocityY = mVelocityHelper.getYVelocity();
       ReactScrollViewHelper.emitScrollEndDragEvent(this, velocityX, velocityY);
+      NativeGestureUtil.notifyNativeGestureEnded(this, ev);
       mDragging = false;
       // After the touch finishes, we may need to do some scrolling afterwards either as a result
       // of a fling or because we need to page align the content