Add per-display RemoteAnimation overrides and flag to disable snapshots

This CL adds a display-level fallback for remoteanimation overrides
and a property to RemoteAnimationAdapter specifying whether it needs
a snapshot for change transitions or not.

During a mode-change, this check for an override and then asks it
whether it needs a snapshot before creating one.

Bug: 113252739
Test: Added AppChangeTransitionTests
Change-Id: I47c933bd08fe512dc6cf029607819e2c908ab4cd