Use mobile code for TV Shell Transitions.

- Uses alpha instead of bounds animation on TV during PiP entry
- Attaches the menu earlier to make sure the PiP immediately
appears in the right position as the menu affects the position.

Bug: 271098548
Bug: 228071323
Test: manual - PiP should fade in instead of being scaled from
fullscreen to the PiP size, PiP should not appear low and then
move up.

Change-Id: I51b6deea3d0e2f2e7166e9df8c98685d6aee82a3