Adding support for loading workspace in the absence of Launcher.

> LoadWorkspace can be called with a LoaderResult which does not bind anything.
> Synchronous bind does not look for a valid page id, and will fallback to the
  current pageId similar to full load flow

Bug: 37616877
Change-Id: If14491dc79c5b85ae1019cc93e4e08759df3387d

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

@@ -47,7 +47,7 @@ import java.util.List;
 /**
  * Task to add auto-created workspace items.
  */
-public class AddWorkspaceItemsTask extends ExtendedModelTask {
+public class AddWorkspaceItemsTask extends BaseModelUpdateTask {
 
     private final Provider<List<Pair<ItemInfo, Object>>> mAppsProvider;