enable MediaProjection Service

this service is required for screen recording to work. Specificially
for WearMediaScreenRecorder to start recording the screen.

BUG: 171561784
Test: N/A (manually check that service has been launched)
Change-Id: I38ecc94d68bf7c0c48a3d57138cf1da4ad890064
(cherry picked from commit fd7a0e8fc1bc1be717f084aec1ef89dc1e67847e)