Player activity notification: move some intialization server-side

Make beginning of player tracking synchronous, init uid/pid/piid
  on the server side, and return the piid.
Anonymize configurations in the getter of active configurations
  when the client isn't privileged.

Test: run cts -m CtsMediaTestCases -t android.media.cts.AudioPlaybackConfigurationTest
Bug: 30955183

Change-Id: I1610ae0067fd26d297057663352e679c8963a2d7