Bring up IME and focus on input when scroll to top.

Do this behind a feature flag AND only when "Always show keyboard" is selected or in prefix state.

Bug: 218846025
Test: keyboard shown when swiping up for QSB and AA+ (both main and work). Keyboard not shown when either the feature flag or Always show keyboard is disabled.
Change-Id: I3df2e0e44a8313eaf749cd6b91b7f9d0b9b80ec3

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

@@ -107,8 +107,7 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
             new RecyclerView.OnScrollListener() {
                 @Override
                 public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
-                    updateHeaderScroll(
-                            ((AllAppsRecyclerView) recyclerView).computeVerticalScrollOffset());
+                    updateHeaderScroll(recyclerView.computeVerticalScrollOffset());
                 }
             };
 
@@ -192,7 +191,6 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
                 reset(true);
             }
         }
-
     }
 
     @Override
@@ -815,6 +813,10 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
         }
     }
 
+    protected void onInitializeRecyclerView(RecyclerView rv) {
+        rv.addOnScrollListener(mScrollListener);
+    }
+
     /** Holds a {@link BaseAllAppsAdapter} and related fields. */
     public class AdapterHolder {
         public static final int MAIN = 0;
@@ -851,7 +853,7 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
             mRecyclerView.setHasFixedSize(true);
             // No animations will occur when changes occur to the items in this RecyclerView.
             mRecyclerView.setItemAnimator(null);
-            mRecyclerView.addOnScrollListener(mScrollListener);
+            onInitializeRecyclerView(mRecyclerView);
             FocusedItemDecorator focusedItemDecorator = new FocusedItemDecorator(mRecyclerView);
             mRecyclerView.addItemDecoration(focusedItemDecorator);
             mAdapter.setIconFocusListener(focusedItemDecorator.getFocusListener());