Added API to mirror display and added sample app.

Added the WMS.mirrorDisplay API to mirror a specified displayId. The
request requires the ACCESS_SURFACE_FLINGER permission.

Added a sample app to demonstrate the useablility of this API and
different ways the mirror SurfaceControl can be used.

Test: mmma tests/MirrorSurfaceTest and install apk
Bug: 131622422
Change-Id: Ic86115786d37473650b3c7ed39cba0bd4c65b281