Create AppForegroundHelper

Create a new helper to deal with application foreground state changes.

1) Rename various Helpers.
2) Move GnssManagerService into location dir.
3) Use new AppForegroundHelper everywhere.
4) Move sendNiRequest to internal API
5) Some refactoring of NetInitiatedActivity

Test: atest AppForegroundHelperTest
Change-Id: Ifffe0e6a34452a18d017c6b190547b904d77b430
16 files changed