Only switch task focus to window's task that was tapped outside current focus

The previous logic would check what Task was at the coordinates that the event
receiver got. This was an issue if a window that was tapped didn't have a Task,
for example, system windows. The Task focus would get switched to the Task that
was behind the tapped window.

This change leverages the new API onPointerDownOutsideFocusLocked. When a down
outside focus occurs, WindowManager will check if the window has a Task + the
check that existed previously, before determining whether the new Task should
get focus.

Fixes: 129571534
Test: Steps from bug
Test: Resize in freeform continues to work.
Change-Id: I73286e03f505cdf37f30fa5914cf24f843a6bc7c