Replace setFinalCrop with temporary layer

- Creates a temporary animation bounds layer when setting up the
  animation in AppWindowToken
- The leash is parented to this new layer if the appStackClipMode
   is set to STACK_CLIP_AFTER_ANIM

Test: Manual test - open activity in split screen
Test: atest FrameworksServicesTests:AppWindowTokenAnimationTests
Change-Id: I6a9cf99832ee868a6e65da0150291d521f5eca35