Fix talkback unable to select pip window buttons

While talkback enabled, single touch would be translated to hover
events, and all touch events would first sent to pip input consumer
then dispatch them to pip menu activity. So we should dispatch these
hover events to dispatchGenericMotionEvent of menu activity to make sure
them would be handled correctly.

- It should unregister PictureInPictureActionReplacingConnection when
  menu activity shown to make sure a11y action can be performed by default.
- Move overridePendingTransition to onCreate to ensure a11y window infos
  can be updated after first time finish.

Bug: 142268623
Test: Enable talkback and launch pip, click buttons on pip window
Test: atest AbstractAccessibilityServiceConnectionTest
Change-Id: I886106d3d36c54e4540e25056c79dad5c82405e8