Transfer PipContentOverlay when swipe to home with Shell transition

Swipe to home animation is played by launcher, but the entering PIP
transition will finished by PipTransition. As a result, we need to
reparent the overlay and fade out the overlay in PipTransition when
enter PIP is finalized, otherwise the overlay will be removed with the
remote transition leash and cause flicker.

Bug: 222030101
Test: verify with swipe to home with Shell transition
Change-Id: Idde3414e3cc5e8193cf7d4da9818e59dc6b4b1c5