Adding new Battery Saver location mode.

When this new mode (LOCATION_MODE_THROTTLE_REQUESTS_WHEN_SCREEN_OFF) is
enabled, LocationManagerService will avoid sending almost all
LocationRequests to providers. The only requests that will continue to
be sent will be providers are the requests that ignore location
settings.

Bug: 121256487
Bug: 122849003
Bug: 119261320
Test: atest android.os.cts.batterysaving.BatterySaverLocationTest
Change-Id: Iee95a6fb5ca11d4db7a0f0661bf3cb1051a5d710