[Catalyst] Internet screen migration

- Add a flag for the migration
- Add the skeleton of the screen

Test: atest NetworkProviderScreenTest
Bug: 372733639
Flag: com.android.settings.flags.catalyst_internet_settings
Change-Id: Ia007b06501ef16e85df3e2f58536e8488d27bb3f

src/com/android/settings/network/NetworkProviderSettings.java

@@ -1508,4 +1508,9 @@ public class NetworkProviderSettings extends RestrictedDashboardFragment
             return android.R.attr.colorControlNormal;
         }
     }
+
+    @Override
+    public @Nullable String getPreferenceScreenBindingKey(@NonNull Context context) {
+        return NetworkProviderScreen.KEY;
+    }
 }