Add ethernet interface details settings subpage

Adds a click listener to the ethernet interface row and displays a
settings subpage with interface connection status.

Flag: com.android.settings.connectivity.ethernet_settings

Test: atest SettingsRoboTests:
com.android.settings.network.NetworkProviderSettingsTest

Change-Id: Id64ce3657b47dd4ca70d425dd3d13227c8468d2c