Implement two pane widget picker

The widget picker design is currently not optimized for large screen form factor devices.
We resolve that by adding a two pane widget picker like that of the design in go/widget-picker-2023.

Bug: 256684299
Test: Make sure to be on a tablet in landscape mode.
        1.Turn on flag LARGE_SCREEN_WIDGET_PICKER.
        2. Press and hold on an empty spot in workspace until the popup menu appears.
        3. Click widgets.
        4. Notice the new two pane layout
Change-Id: Ia3ea17dc320f72f9bc5dea52399ff51d9161602b

src/com/android/launcher3/FastScrollRecyclerView.java

@@ -63,6 +63,9 @@ public abstract class FastScrollRecyclerView extends RecyclerView  {
 
     public void bindFastScrollbar() {
         ViewGroup parent = (ViewGroup) getParent().getParent();
+        if (parent.findViewById(R.id.fast_scroller) == null) {
+            parent = (ViewGroup) parent.getParent();
+        }
         mScrollbar = parent.findViewById(R.id.fast_scroller);
         mScrollbar.setRecyclerView(this, parent.findViewById(R.id.fast_scroller_popup));
         onUpdateScrollbar(0);