Defer always on top state when task gets maximized

This CL enables always on top to be restored/deferred when
stacks switch between freeform and fullscreen.

Bug: 110494387
Test: ActivityStackTests
Test: DisplayContentTests
Test: go/wm-smoke
Change-Id: Iccb9824f845dea4925fac5d5dcb5eeaab2acdfcd
5 files changed