Adding support for top padding in BaseRecyclerView. The scrollbar is

drawn below the top padding.
Also adding callback for getting the all-apps vertical pull range
so that it can be controlled by SearchUiManager

Bug: 37616877
Change-Id: Ib4642073f3e92f6676caede3bddd652fda89c86f

src/com/android/launcher3/allapps/AllAppsGridAdapter.java

@@ -161,11 +161,6 @@ public class AllAppsGridAdapter extends RecyclerView.Adapter<AllAppsGridAdapter.
             }
             return extraRows;
         }
-
-        @Override
-        public int getPaddingBottom() {
-            return mLauncher.getDragLayer().getInsets().bottom;
-        }
     }
 
     /**