Use local leash to animate PiP activity surface

Currently shell is not aware of letterbox info of activity.
Especially PiP animation assume the surface is task which
should be put at 0,0 in either task display area or a
multi-window container after expanding.

By using a local leash, the position of activity surface won't
be erased by the end of pip animation, and the animation will
look better by including the area of activity offset.

Bug: 280028520
Test: In a ignore-orientation display or split screen.
      Task[A,B], B requested fixed orientation to trigger letterbox.
      B enter PiP, then then expand to original position.
      The offset from letterbox should not be changed.
Change-Id: I1a24703ce0d9976d0f5dfeda0569226a5afa908c