Make Activites touch opaque - DO NOT MERGE

Block touches from passing through activities by adding a dedicated
surface that consumes all touches that would otherwise pass through the
bounds availble to the Activity.

Bug: 194480991
Test: atest CtsWindowManagerDeviceTestCases:ActivityRecordInputSinkTests
Test: atest CtsWindowManagerDeviceTestCases:CrossAppDragAndDropTests
Test: atest CtsWindowManagerDeviceTestCases:PinnedStackTests
Test: Manually ran through go/wm-smoke (verified pip and splitscreen
still work)
Test: Manually verfied that freeform windows work and don't consume
touches outside their bounds

Change-Id: I01b35e34a63868dead4e728a3d359ae0942302f9