Add top-level Communal settings.

This change adds a new top-level setting, of which the availability is
controlled by a build time config value. It also registers the new
communal category so that prebuilt packages can inject preferences into
it.

Bug: 261641080
Test: verified on device that communal settings show up on top level
Test: atest ScreenSaverPreferenceControllerTest
Change-Id: Idf79ae5b89ecc3498373de56a677b4876fb121c3

src/com/android/settings/communal/CommunalPreferenceController.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+package com.android.settings.communal;
+
+import android.content.Context;
+
+import com.android.settings.R;
+import com.android.settings.core.BasePreferenceController;
+
+/**
+ * Controls the top-level Communal settings preference.
+ */
+public class CommunalPreferenceController extends BasePreferenceController {
+    public CommunalPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return mContext.getResources().getBoolean(R.bool.config_show_communal_settings)
+                ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+}