Reland: Clear transitions for app windows display change.

This prevents unwanted animations from running for windows on the new
display that are no longer relevant.
Also,
- Transfer the opening app token transition to the new display so that
it can be eventually made visible on that display
- Clean-up TODO relating to moving VR activity to main display, so that
the right states are set.

Bug: 128449959
Test: VrDisplayTests
Test: manual - launch activity with options moving between virtual and
default display, atest WmTests

Change-Id: I285c6742839d38e76322621b9c2a1d7f313cd6f8