Makes all custom caption settings unsearchable when custom captions are not active.

Unifies all custom caption controllers under a base controller, whose searchability is directly determined by CaptionHelper#getCustomCaptionAvailability().

Test: atest CaptionHelperTest
Bug: 353757664
Flag: com.android.settings.accessibility.fix_a11y_settings_search
Change-Id: If44e6eca4c72aa4413cd0a6e8735dbb22c7abe62

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

@@ -0,0 +1,35 @@
+/*
+ * 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 com.android.settings.core.BasePreferenceController;
+
+public class BaseCaptioningCustomController extends BasePreferenceController {
+    protected final CaptionHelper mCaptionHelper;
+
+    public BaseCaptioningCustomController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+        mCaptionHelper = new CaptionHelper(context);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return mCaptionHelper.getCustomCaptionAvailability();
+    }
+}