Change PIP exit transition to a scale and uncrop

If there's a source hint rect available, perform an uncrop
and scale animation from PIP -> Fullscreen similar to the
enter transition.

Bug: 167447693
Test: restore PIP to fullscreen, see scale and uncrop
animation instead of squishiness

Change-Id: Idce6d6d6d1f365f0a3adc5256a980066e721659e