Move unrestricted data summary to DataSaverController

DataSaverController currently used in 2 pages,
- Network & internet > Data Saver
- Apps > Special app access

This helps unify the logic, and instead of showing on "Special app
access", this summary shows on "Unrestricted data" is make more sense.

Bug: 280280596
Test: Manually on above pages
Test: Unit test
Change-Id: Ia151ed8179a250f8f20cc5041f9383fffebdab10

src/com/android/settings/applications/AppDashboardFragment.java

@@ -66,7 +66,6 @@ public class AppDashboardFragment extends DashboardFragment {
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
-        use(SpecialAppAccessPreferenceController.class).setSession(getSettingsLifecycle());
         mAppsPreferenceController = use(AppsPreferenceController.class);
         mAppsPreferenceController.setFragment(this /* fragment */);
         getSettingsLifecycle().addObserver(mAppsPreferenceController);