Implement no animation expand pip (2/2)

Prevent any flickers upon early draws when
exiting PiP via expand
(with PiP2 experimental flag being on).

This is done by utilizing the current freezing and snapshot
mechanism during collection phase. The snapshot surface is also
appropriately reparented and repositioned.
This needs to be done since reparenting of an activity removes
the original parent along with the snapshot attached to it.

Fore more info see go/pip2-transitions

Bug: 307784067
Test: adb shell am broadcast -a \
	com.android.wm.shell.pip2.phone.PipScheduler
Change-Id: I48943bb90dcead045ad86da4bb85b345a9996c0e