[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/PanelContentCallback.java

@@ -37,4 +37,9 @@ public interface PanelContentCallback {
      * It will be called when panel requests to close itself.
      */
     void forceClose();
+
+    /**
+     * It will be called when panel requests to change the title.
+     */
+    void onTitleChanged();
 }