WM: Adjust TaskSnapshot for cutout layout

Makes TaskSnapshot work even when the main window top-left
position is not the same as the stack's.

Bug: 65689439
Test: Enable cutout, open Gmail, open Recents, verify transition did not jump in the end, open Gmail from recents, verify transition did not jump in the end.
Change-Id: I48053f551ed1c118764aa30e0b6408db64d4a5f1
2 files changed