Add support for carrier wifi in UI.

Make changes to the UI, so that it does not ask for additional
information while connecting to Carrier Wifi. Also, indicate in wifi
picker if the wifi is a carrier network.

Bug:30988281
Test: make RunSettingsRoboTests -j40 ROBOTEST_FILTER=WifiConfigControllerTest
Test: manual
Change-Id: Iecbcd77d400264aaaa16a6a95a2093d58f2748f9