Introduce MemoryUsagePreferenceController

- Use a hard-coded preference instead of injecting
 so that search can index the preference
 - Create a preference controller to update the summary

Change-Id: Idf822ccbb7a58a9ec561d5c2c2948dbc3272544f
fixes: 36463051
Test: Manual using settings app

src/com/android/settings/development/DevelopmentSettingsDashboardFragment.java

@@ -352,6 +352,7 @@ public class DevelopmentSettingsDashboardFragment extends RestrictedDashboardFra
             Activity activity, Lifecycle lifecycle, DevelopmentSettingsDashboardFragment fragment,
             BluetoothA2dpConfigStore bluetoothA2dpConfigStore) {
         final List<AbstractPreferenceController> controllers = new ArrayList<>();
+        controllers.add(new MemoryUsagePreferenceController(context));
         controllers.add(new BugReportPreferenceControllerV2(context));
         controllers.add(new LocalBackupPasswordPreferenceController(context));
         controllers.add(new StayAwakePreferenceController(context, lifecycle));