Adjust animation bounds for AE on expanding PiP

When expanding PiP back to ActivityEmbedding setup, the bounds to
animate from transition is in absolute screen coordinates while we're
animating to its parent TaskFragment. Adjust both the start and end
bounds accordingly if that's the case.

Flag: com.android.wm.shell.enable_pip2
Bug: 420998087
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/hNeqWhkP6Vdxs82oKv4lTz
Test: Use the Demo app to enter and expand PiP, see Video
Change-Id: Icd3c193f06fc840db28d01962bca3c693e40db24