[Settings] Add voice call status and VoLTE mode detection into VoLTE UI test case

1. VoLTE UI should gray out during voice call.
2. UI should be invisible when VoLTE mode mismatch.

Bug: 172781455
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=Enhanced4gBasePreferenceControllerTest
Merged-In: I8b6a212dc727f1ab78f4dd280cb41966b7054180
(cherry picked from commit 227329b2)
Change-Id: I1bd239b6434038323a0689e2bc3bf05182bfcd45