[Provider Model] Add connected ethernet network preference

- Show the preference if connected to ethernet network

- Hide the preference if not connected to ethernet network

- Screenshot:
  https://screenshot.googleplex.com/5ZkZXnTr9Hcfsyt

Bug: 176796623
Test: manual test
- atest ConnectedEthernetNetworkControllerTest
- make RunSettingsRoboTests ROBOTEST_FILTER=NetworkProviderSettingsTest

Change-Id: I0f062eb2ee4898976f5e7a1c3f2c4061b60a3126