Adding a DB update path to handle the QSB position change

> Renamed the id of 1st screen to 0 and making space for the QSB
by running the grid migration task.
> Added a feature flag to easily disable the QSB-in-workspace behavior

Change-Id: Ie3369f0d4433d916e9d6215d414770d4333f3e26

src/com/android/launcher3/Workspace.java

@@ -510,6 +510,9 @@ public class Workspace extends PagedView
      * @param qsb an exisitng qsb to recycle or null.
      */
     public void bindAndInitFirstWorkspaceScreen(View qsb) {
+        if (!FeatureFlags.QSB_ON_FIRST_SCREEN) {
+            return;
+        }
         // Add the first page
         CellLayout firstPage = insertNewWorkspaceScreen(Workspace.FIRST_SCREEN_ID, 0);
 
@@ -909,7 +912,8 @@ public class Workspace extends PagedView
             long id = mWorkspaceScreens.keyAt(i);
             CellLayout cl = mWorkspaceScreens.valueAt(i);
             // FIRST_SCREEN_ID can never be removed.
-            if (id > FIRST_SCREEN_ID && cl.getShortcutsAndWidgets().getChildCount() == 0) {
+            if ((!FeatureFlags.QSB_ON_FIRST_SCREEN || id > FIRST_SCREEN_ID)
+                    && cl.getShortcutsAndWidgets().getChildCount() == 0) {
                 removeScreens.add(id);
             }
         }