Move recentsAnimationController to shell

This moves the IRecentsAnimationController impl for
shell-transitions into shell. This comes with a number of
benefits. The most immediate one is that we can properly
manage the recents animation lifecycle -- in particular,
we can cancel/restart the animation when recents activity
is launched and manage failsafe logic more robustly. This
includes situations where launcher swaps recents activity
around or users change.

Longer term, this lets us have synchronized monitoring of
incoming transitions so we can avoid IPC races. In particular,
we can have better coordination between recents and other
transitions like split-screen.

Bug: 269691848
Test: existing tests pass. This is mostly just moving code.
Change-Id: I937b6c2594a9fb78a3a7bee684d34ab1905b9c0b