Override animation background with app override color

Order of color to use:
1. Color set with Activity.overridePendingTransition.
2. Color set with the new Jetpack APIs.
3. Task background color.

Bug: 263047900
Test: verify with demo app
Change-Id: I3441ef3705f5a2dd54e855999a8a0c0055f677bc
2 files changed