Use sourceRectHint to calculate scale when enter PiP

This is to patch the entering PiP transition with YT tablet UI, which is
used in unfolded state and/or tablets landscape mode.

Changed also to use SurfaceControl.Transaction#setCrop instead of
deprecated setWindowCrop.

Bug: 198309223
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/eODHpvqAQPfbwjFamtRYC1
Test: manual, see video
Change-Id: I6fbfea110f9a73faf05ebeb90773dcee58b41328