Binding Taskbar directly from Launcher model

This allows taskbar to be loaded even in case of 3P Launchers
and removes dependency on LauncherActivity lifecycle

Bug: 187353581
Bug: 188788621
Test: Manual
Change-Id: I5a0988e0697b41677d4c58f0213aef14ec0c0972

src/com/android/launcher3/model/BgDataModel.java

@@ -476,6 +476,11 @@ public class BgDataModel {
         default void bindAppsAdded(IntArray newScreens,
                 ArrayList<ItemInfo> addNotAnimated, ArrayList<ItemInfo> addAnimated) { }
 
+        /**
+         * Called when some persistent property of an item is modified
+         */
+        default void bindItemsModified(List<ItemInfo> items) { }
+
         /**
          * Binds updated incremental download progress
          */