Fade the TV PiP menu surfaces during enter/exit.

With the bounds entry animation the surfaces appeared before/after the
bounds animation, however with the change to the alpha entry animation
we want the menu surfaces to fade in/out together with the PiP.

This change works with both the shell transitions enabled and disabled.

Bug: 271098548
Bug: 228071323
Test: manual - do once with shell transitions enabled and disabled:
start a PiP -> PiP menu surfaces should fade in gradually with PiP
content, close PiP via close button -> menu surfaces should fade out

Change-Id: I51fcfe006a672e9c2a094f6657d1552a273c84cf