Move Bluetooth battery stats tracking (2/2)

Move Bluetooth battery stats tracking to AppScanStats for a more
unified tracking system.

Bug: 37720787
Test: cts-tradefed run cts-dev -m CtsIncidentHostTestCases -t com.android.server.cts.BatteryStatsValidationTest#testBleScans
      Perform BLE scan and check battery stats
Change-Id: I6129a83d275c7d72edc6abfc5cc72641adde8767