PiP animation: Move window with resize when ending animation.

At the end of the animation (when going from larger to smaller),
we are left with a scaled surface, that we want to seamlessly
resize to an unscaled surface of the new size. Because we have scaled
the shadow region of the surface, the position of the content
will differ before and after the resize applies. We use new
SurfaceFlinger API to cause position updates to apply after
resize. Because we have to switch into SCALING_MODE_FREEZE,
we could end up prematurely cropping the window, so we
switch to using screen space crop for the pinned stack.

Bug: 28899837
Change-Id: I9b762a237413e4fa3d432e67d30c7125bfef484c