Allows for system navigation settings to be added dynamically.

This allows for controller-backed preferences to be added or
overridden via xml.

Similarly, if the controllers cause all of the preferences for
2 or 3 button nav to be unavailable, we hide the settings button.

Bug: 324036308
Test: Manual and unit tests
Flag: NA
Change-Id: I2371f3173076172489966728ac69c8767570cd56

tests/robotests/res/xml-mcc997/location_settings.xml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:settings="http://schemas.android.com/apk/res-auto"
+    android:key="fake_title_key"
+    android:title="screen_title">
+
+    <Preference
+        android:key="key1"
+        android:title="title"
+        android:icon="@drawable/ic_android"
+        android:summary="summary1"
+        settings:controller="com.android.settings.core.UnavailablePreferenceController"/>
+
+    <Preference
+        android:key="key2"
+        android:title="title"
+        android:icon="@drawable/ic_android"
+        android:summary="summary2"
+        settings:controller="com.android.settings.core.UnavailablePreferenceController"/>
+
+</PreferenceScreen>