Fixing folder focus logic

> Folder items no longer remain in a linear order when a folder
gets rearranged, and se we need to use createSparseMatrix instead
of createFullArray. Also because of this we need to use getChildAt(x, y)
instead of getChildAt(index)
> Removing traces of AppsCustomizePage (all apps) from FocusHelper

Change-Id: I9007f6b95cb823e27ef4a43ce725fda8ef1b7cf8

src/com/android/launcher3/ShortcutAndWidgetContainer.java

@@ -177,7 +177,7 @@ public class ShortcutAndWidgetContainer extends ViewGroup {
         child.measure(childWidthMeasureSpec, childheightMeasureSpec);
     }
 
-    private boolean invertLayoutHorizontally() {
+    public boolean invertLayoutHorizontally() {
         return mInvertIfRtl && isLayoutRtl();
     }