Introduce TaskFragment transition type

Previously AppTransitionController didn't recognize TaskFragment
transitions, so it uses Task opening/closing animation for
TaskFragment transitions.
This CL introduces and uses TaskFragment transition if the animation
target is TaskFragment. The new transition type can be used for registering
RemoteAnimation implemented by TaskFragmentOrganizer as well.
This CL also provides a fallback mechanism for TaskFragment transitions
if the RemoteAnimation fails or one of opening/closing animation target
is not a pure organized TaskFragment.

Bug: 194649929
Test: manual - the reproducible step in b/194649929#comment1
Test: atest WmTests:AppTransitionTests AppTransitionControllerTest
Change-Id: I0094694fa5cd95d8bbb7da94d2aaf7aac6e1fe09