Input: Override touchable region bounds with surface bounds 1/2

Take advantage of the surface flinger layer hierarchy to set touchable
region.

- Let a client set a surface touchable region to its own bounds.
- Let a client set a surface touchable region to another surface bounds.
- Let a client bound its touchable region to a surface.

Test: go/wm-smoke
Test: existing tests

Change-Id: Id5ef8b35f4779861c1537811a045a44ee2394fdf