Add support for remote transition playback in shell transitions

This adds IRemoteTransition interface for other processes (like
launcher) to register for playing transition animations.

Then there are 2 supported ways to "register":

1. Is to attach an IRemoteTransition to ActivityOptions. To
   support this pathway, requestStartTransition now takes a
   TransitionRequest object which can contain whatever info
   is needed at the time. One piece of that is the passed-in
   IRemoteTransition.

2. Is to register directly with shell (via systemuiproxy for
   now) with a TransitionFilter. This filter allows shell
   transitions to dispatch a transition to a remote without
   need to make queries over binder.

This also hooks up launcher animations by converting the new
transition info to the old RemoteAnimationTargetCompat stuff.

Bug: 169035082
Test: launch app from launcher and observe the icon animation.
      atest ShellTransitionTests
Change-Id: I8014a6f46cffda3a48a1a4ae101e2643078f4a14