Allow TRANSIT_TO_FRONT to enter PiP if needed

Make sure TO_FRONT transitions with a task change
in WINDOWING_MODE_PINNED are resolved as enter PiP
transitions to be handled by PipTransition handler.

Bug: 308054074
Test: use ag/26668330 CP to test for breakage fix
  (instructions provided in that same WIP CL as well)
Change-Id: I5eda8d4a0e88428025c1151b06d8e6f337526ee7