[Provider Model] Add new API to detect

1. current connection is mobile data
 - remove the SubscriptionsPreferenceController#activeNetworkIsCellular() and move into MobileNetworkUtils
2. isProviderModel API
 - Add it in Util for Provider Model
3. isWiFiCallingEnabled
 - remove WifiCallingPreferenceController#isWifiCallingEnabled() and move into MobileNetworkUtils
4. Add nes test case for MobileNetworkUtils

Bug: 171873895
Test: atest -c MobileNetworkUtilsTest
Change-Id: I4bfdf0537fe07d064d6c0ba4a2c44b4a4f158d91