[Provider Model] Dynamically update the Internet Panel title

- Change from "Internet" to "Airplane mode networks"

- Screenshot:
  https://screenshot.googleplex.com/gk3RBcjPsXq5NTk

Bug: 176803442
Test: manual test
- atest InternetConnectivityPanelTest
- make RunSettingsRoboTests ROBOTEST_FILTER=PanelFragmentTest

Change-Id: Ifb2c24434e480861fc7c3eaece683d49eb99013e

src/com/android/settings/panel/PanelFragment.java

@@ -514,6 +514,13 @@ public class PanelFragment extends Fragment {
             getFragmentActivity().finish();
         }
 
+        @Override
+        public void onTitleChanged() {
+            ThreadUtils.postOnMainThread(() -> {
+                mTitleView.setText(mPanel.getTitle());
+            });
+        }
+
         @VisibleForTesting
         FragmentActivity getFragmentActivity() {
             return getActivity();