[Accessibility] Add contrast control screen UI and setup entry point

Bug: 241805782
Test: atest, local raven device
Screenshot: attached on bug
Flag: aconfig
com.android.settings.accessibility.enable_color_contrast_control

Change-Id: I7fcc01b822b460c6585c41a5831575ba0ffbcc93

src/com/android/settings/accessibility/ContrastPreferenceController.java

@@ -0,0 +1,38 @@
+/*
+ * 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.accessibility;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+
+import com.android.settings.core.BasePreferenceController;
+
+/**
+ * Controller for {@link ColorContrastFragment}.
+ */
+public class ContrastPreferenceController extends BasePreferenceController {
+
+    public ContrastPreferenceController(@NonNull Context context, @NonNull String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return Flags.enableColorContrastControl() ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+}