Re-add WiFi Calling preference controller

- WiFi calling preference controller was incorrectly removed
from MobileNetworkSettings.
- It was still accessible from Calls & SMS fragment.

Bug: 253698238
Test: Live test by flashing build on Pixel 7
Change-Id: I42b2ca26dfb0bf39ac9a0ec0107f3323d7dfc61b

src/com/android/settings/network/telephony/MobileNetworkSettings.java

@@ -280,6 +280,8 @@ public class MobileNetworkSettings extends AbstractMobileNetworkSettings impleme
 
         final VideoCallingPreferenceController videoCallingPreferenceController =
                 use(VideoCallingPreferenceController.class).init(mSubId);
+        use(CallingPreferenceCategoryController.class).setChildren(
+                Arrays.asList(wifiCallingPreferenceController, videoCallingPreferenceController));
         use(Enhanced4gLtePreferenceController.class).init(mSubId)
                 .addListener(videoCallingPreferenceController);
         use(Enhanced4gCallingPreferenceController.class).init(mSubId)