Add a new system service: MediaCommunicationService

Bug: 175511943
Test: MediaCommunicationService can run.
      'adb shell service list' shows the service.
Change-Id: I81a1e11d96d1d30a29760507be6fe04592afcf70
Merged-In: I81a1e11d96d1d30a29760507be6fe04592afcf70