Reland add FeatureProvider for SyncAcrossDevices Settings integration.

Prior CL ag/26930404 was reverted because an unused class was
trimmed in AOSP, causing test cases to throw NoClassDefFoundError
exceptions. This CL combines ag/26930404 and ag/26995936 to address
the failure.

Bug: 330498032
Test: atest FakeFeatureFactory, atest SyncAcrossDevicesPreferenceControllerTest
Change-Id: I0a7ebccdebcad20e06d7542d7c4a0005885f393b

src/com/android/settings/notification/syncacrossdevices/SyncAcrossDevicesFeatureProviderImpl.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2024 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.notification.syncacrossdevices;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+/** Default implementation for {@link SyncAcrossDevicesFeatureProvider} */
+public class SyncAcrossDevicesFeatureProviderImpl implements SyncAcrossDevicesFeatureProvider {
+
+    @Override
+    @Nullable
+    public SyncAcrossDevicesFeatureUpdater getSyncAcrossDevicesFeatureUpdater(
+            @NonNull Context context,
+            @NonNull SyncAcrossDevicesFeatureCallback featurePreferenceCallback) {
+        return new SyncAcrossDevicesFeatureUpdater() {};
+    }
+}