TouchHandler for hiding dream overlay complications.

This changelist introduces HideComplicationTouchHandler, which is
responsible for monitoring touches on the dream overlay and determining
when complications should be hidden. When a touch ends, the
DreamTouchHandler also handles restoring complication visibility.

Test: atest HideComplicationTouchHandler
Fixes: 214292772
Change-Id: Ib80ed9d6c351503ef5f9910b9870c4a5672b96d2