Extract out common adapter logic to support different AllApps layouts

Test: Manual tests. Refactoring, all existing tests should pass.
Bug: 216150568
Change-Id: I1068e75d0b4a33d402a7d68e237d2484ab3a1e01

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

@@ -256,4 +256,11 @@ public class ActivityAllAppsContainerView<T extends BaseDraggingActivity> extend
         layoutParams.removeRule(RelativeLayout.BELOW);
         layoutParams.addRule(RelativeLayout.ALIGN_PARENT_TOP);
     }
+
+    @Override
+    protected BaseAllAppsAdapter getAdapter(AlphabeticalAppsList<T> mAppsList,
+            BaseAdapterProvider[] adapterProviders) {
+        return new AllAppsGridAdapter<>(mActivityContext, getLayoutInflater(), mAppsList,
+                adapterProviders);
+    }
 }