Moving the QSB to the workspace grid.

The QSB will only be resent on the first screen of the workspace
covering the full width of the first row. If will not be movable.
The first screen of the workspace will not be movable.
The searchDropTargetBar no longer contains the QSB (it can be
renamed in aseparate cl).

Refactoring all QSB related logic by moving it to a custom view
inflated only using xml.
Change-Id: Icb4fd6eb855df1af15f685961c38351bf4fd4f4a

src/com/android/launcher3/CellLayout.java

@@ -2708,7 +2708,7 @@ public class CellLayout extends ViewGroup implements BubbleTextShadowHandler {
 
         /**
          * Indicates whether this item can be reordered. Always true except in the case of the
-         * the AllApps button.
+         * the AllApps button and QSB place holder.
          */
         public boolean canReorder = true;