-Makes geofence manager work synchronously so that testing is not flaky
-Adopts ListenerMultiplexer for geofence listeners so that logic is
shared across location code
-Adds support for location blacklisting and background users
-Substantially reduces the CPU overhead of maintaining listeners
-Adds worksource support to geofencing so power blame is done correctly
-Adds new feature id for geofencing
Test: manual + presubmit
Change-Id: If55bc18f202debf7dd183f0120a24e8f75623ce8
fb272095ad