Implement wifi emergency calling warning

The warning is shown when there is no service, and the carrier requires the message to be shown because they cannot make emergency call over wifi.

Bug: 68030294
Test: Unit tests, integration tests.
PiperOrigin-RevId: 190241868
Change-Id: Ia6b838ac1e8e62ad6b40d97c1cf1a970491c1e6f