Merge changes I5c61c3c0,I7d6f821b,I2a7d5e51

* changes:
  WifiScanningSevice: Create multiple scanner impls
  WifiScanningService: Move ScannerImpl setup/teardown
  WifiScanningService: Handle ScanEventHandler callbacks in separate class
tree: 79172562990baf928be6acd24c4630efe6ec3f1c
  1. service/
  2. PREUPLOAD.cfg