Use SurfaceControl as token to register a SurfaceControlInputReceiver

Instead of getting back an IBinder that's used to unregister the
receiver, the SC itself can be the id into the map. The client token
still needs to be created and retrieved for testing to ensure we match
the token when looking for the layer in the window infos list.

Test: SurfaceControlInputReceiverTests
Bug: 320506582
Change-Id: I516bbff349c7ad3639ab14350d96112c22e1d6dc