launcher: show smartspace date card on Wallpaper & style

Smartspace requires a lot of information to show cards, and it shouldn't
be required to show a preview for the user on how the home screen looks
like. This changes that to always use the date card from smartspace.

Fixes: 197328474
Test: open Wallpaper & style
Change-Id: I4718a1c0397172f654b7b6b4beb96b50b3b9eeb3

res/layout/qsb_preview.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2021 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<com.android.launcher3.qsb.QsbContainerView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="0dp"
+    android:id="@id/search_container_workspace"
+    android:padding="0dp" >
+
+    <fragment
+        android:name="com.android.launcher3.qsb.QsbContainerView$QsbFragment"
+        android:layout_width="match_parent"
+        android:tag="qsb_view"
+        android:layout_height="match_parent"/>
+</com.android.launcher3.qsb.QsbContainerView>

src/com/android/launcher3/graphics/LauncherPreviewRenderer.java

@@ -511,8 +511,8 @@ public class LauncherPreviewRenderer extends ContextWrapper
         // Add first page QSB
         if (FeatureFlags.QSB_ON_FIRST_SCREEN) {
             CellLayout firstScreen = mWorkspaceScreens.get(FIRST_SCREEN_ID);
-            View qsb = mHomeElementInflater.inflate(
-                    R.layout.search_container_workspace, firstScreen, false);
+            View qsb = mHomeElementInflater.inflate(R.layout.qsb_preview, firstScreen,
+                    false);
             CellLayout.LayoutParams lp =
                     new CellLayout.LayoutParams(0, 0, firstScreen.getCountX(), 1);
             lp.canReorder = false;