Fix retain cycle in RCTFabricSurface

Summary:
Changelog: [internal]

Fix retain cycle caused by chain: `RCTSurfaceTouchHandler` -> `RCTSurfaceTouchHandler._rootComponentView` -> `RCTSurfaceTouchHandler`

`RCTSurfaceTouchHandler._rootComponentView` calls `addGestureRecognizer` with `RCTSurfaceTouchHandler` as a parameter which, according to documentation, strongly holds onto gesture recogniser.

https://www.internalfb.com/intern/diffusion/FBS/browsefile/master/xplat/js/react-native-github/React/Fabric/RCTSurfaceTouchHandler.mm?lines=189

For details about `addGestureRecognizer`, refer to https://developer.apple.com/documentation/appkit/nsview/1483749-addgesturerecognizer?language=objc#

Reviewed By: shergin

Differential Revision: D23704441

fbshipit-source-id: b1ab0feff552eaf10c1c71a931690c5258ce87cf

React/Fabric/Surface/RCTFabricSurface.mm

@@ -83,6 +83,7 @@ - (BOOL)stop
  }
 
  [_surfacePresenter unregisterSurface:self];
+ [_touchHandler detachFromView:_view];
  return YES;
 }