Implement Settings#checkAndNoteChangeNetworkStateOperation on CS

Connectivity is becoming a mainline module in S and
ConnectivityManager#enforceChangePermission is using
Settings#checkAndNoteChangeNetworkStateOperation for performing a
strict and comprehensive check of whether a calling package is
allowed to change the state of network. However, Mainline modules
are not allowed to use non-formal APIs, fortunately CS is the
only caller of this ConnectivityManager#enforceChangePermission.
Thus, implement the Settings API on ConnectivityService and remove
the ConnectivityManager#enforceChangePermission and
Settings#checkAndNoteChangeNetworkStateOperation.

Bug: 178565313
Test: atest FrameworksNetTests
Change-Id: I6f03398c1735b89470ad5bdbe3a036929daeb53c