[Provider Model] Show "!" icon when Wi-Fi is not validated (panel)

- Screenshot:
  https://screenshot.googleplex.com/BLNcfXiJFnuoT9N

Bug: 185454486
Bug: 185637977
Bug: 186543071
Test: manual test
atest -c ProviderModelSliceTest
make RunSettingsRoboTests ROBOTEST_FILTER=WifiSliceTest

Change-Id: Idff6bb8b394db5553cf399d2020aa28d9dedfc74