Add onPointerDownOutsideFocus for events outside the focused window (4/4)

Moved the logic that was handled in the TaskTapPointerEventListener that
handled switching displays when focus change into
WMS.onPointerDownOutsideFocus. The new method is called when InputDispatcher
notifies system server that a non focused window received a pointer down input
event. This allows WMS to check if the new window can receive focus before
changing display focus.

Test: Back button with ActivityView closes IME instead of entire
Activity.
Test: WindowFocusTests#testTapFocusableWindow,testTapNonFocusableWindow
Bug: 122535136

Change-Id: I4273ebc9b6d0eaf572864ad81461e6017053cfab