Expose some APIs from ConnectivityManager

- Expose setRequireVpnForUids to Vpn.java
- Expose setLegacyLockdownVpnEnabled to LockdownVpnTracker.java
- Expose requestRouteToHostAddress to
  GnssNetworkConnectivityHandler.java

Bug: 182963397
Test: m
Change-Id: I1fb5ecfbe37878ba3534e6c6c7599ca29db2735c
Merged-In: I1fb5ecfbe37878ba3534e6c6c7599ca29db2735c
  (cherry-picked from ag/13927657)