Create a new region picker page

1. The region which is selected in region picker will also apply to the first locale.
2. When a user change the first locale, the region of the first locale will be updated to the region picker.

Bug: 385047778
Flag: com.android.settings.flags.regional_preferences_api_enabled
Test: check hsv
Change-Id: I001e0910ce9d1601513ed2f52e6ee30d3551859f

res/xml/language_and_region_settings.xml

@@ -51,6 +51,13 @@
       android:title="@string/regional_preferences_category_title"
       settings:controller="com.android.settings.regionalpreferences.RegionalPreferencesCategoryController">
 
+    <Preference
+        android:key="region_preference"
+        android:title="@string/region_picker_preference_title"
+        settings:controller="com.android.settings.regionalpreferences.RegionPreferenceController"
+        settings:fragment="com.android.settings.regionalpreferences.RegionPickerFragment">
+    </Preference>
+
     <Preference
         android:key="temperature_preference"
         android:title="@string/temperature_preferences_title"

res/xml/system_region_picker.xml

@@ -0,0 +1,35 @@
+<?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"
+    android:key="key_system_region_picker_page"
+    android:title="@string/region_picker_title">
+
+  <com.android.settingslib.widget.TopIntroPreference
+      android:key="key_region_picker_sub_title"
+      android:title="@string/region_picker_sub_title"
+      android:persistent="false"/>
+
+  <PreferenceCategory
+      android:key="system_region_suggested_category"
+      android:title="@string/suggested_region_title"/>
+
+  <PreferenceCategory
+      android:key="system_region_all_supported_category"
+      android:title="@string/all_supported_region_title"/>
+
+</PreferenceScreen>