[Provider Model] Add Internet preference to replace Wi-Fi preference

- Change title from "Wi-Fi" to "Internet"
- Remove Wi-Fi switch
- Screenshot:
  https://screenshot.googleplex.com/9tmXYQXKSsuGwEY
  https://screenshot.googleplex.com/5uMCeruXsX3gP9j

Bug: 172295984
Test: manual test
  atest -c InternetPreferenceControllerTest
  make RunSettingsRoboTests ROBOTEST_FILTER=NetworkDashboardFragmentTest
Change-Id: Ie4a3c9aff45fbe7b28594afc9c603e6df57300bf