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/CommunalDashboardFragment.java

@@ -0,0 +1,44 @@
+/*
+ * 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.app.settings.SettingsEnums;
+
+import com.android.settings.R;
+import com.android.settings.dashboard.DashboardFragment;
+
+/**
+ * Dashboard fragment for the top-level Communal settings.
+ */
+public class CommunalDashboardFragment extends DashboardFragment {
+    private static final String TAG = "CommunalFragment";
+
+    @Override
+    public int getMetricsCategory() {
+        return SettingsEnums.COMMUNAL_MODE_SETTINGS;
+    }
+
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.communal_settings;
+    }
+
+    @Override
+    protected String getLogTag() {
+        return TAG;
+    }
+}