Move the "Dark theme" preference into the "Color and Motion" page.

Bug: 221168615
Test: manual test
Change-Id: Ia2d88c0ee03fed97843fef39c92fe22367c67e71
diff --git a/res/xml/accessibility_color_and_motion.xml b/res/xml/accessibility_color_and_motion.xml
index f251d1e..1e3a51f 100644
--- a/res/xml/accessibility_color_and_motion.xml
+++ b/res/xml/accessibility_color_and_motion.xml
@@ -39,6 +39,16 @@
         settings:keywords="@string/keywords_color_inversion"
         settings:controller="com.android.settings.accessibility.ColorInversionPreferenceController"/>
 
+    <com.android.settings.display.darkmode.DarkModePreference
+        android:key="dark_ui_mode_accessibility"
+        android:icon="@drawable/ic_dark_ui"
+        android:title="@string/dark_ui_mode"
+        android:fragment="com.android.settings.display.darkmode.DarkModeSettingsFragment"
+        android:widgetLayout="@null"
+        settings:widgetLayout="@null"
+        settings:controller="com.android.settings.display.DarkUIPreferenceController"
+        settings:searchable="false"/>
+
     <SwitchPreference
         android:key="toggle_disable_animations"
         android:persistent="false"
diff --git a/res/xml/accessibility_settings.xml b/res/xml/accessibility_settings.xml
index 22226a1..2e253e2 100644
--- a/res/xml/accessibility_settings.xml
+++ b/res/xml/accessibility_settings.xml
@@ -60,16 +60,6 @@
             settings:keywords="@string/keywords_reduce_bright_colors"
             settings:controller="com.android.settings.accessibility.ReduceBrightColorsPreferenceController"/>
 
-        <com.android.settings.display.darkmode.DarkModePreference
-            android:key="dark_ui_mode_accessibility"
-            android:icon="@drawable/ic_dark_ui"
-            android:title="@string/dark_ui_mode"
-            android:fragment="com.android.settings.display.darkmode.DarkModeSettingsFragment"
-            android:widgetLayout="@null"
-            settings:widgetLayout="@null"
-            settings:controller="com.android.settings.display.DarkUIPreferenceController"
-            settings:searchable="false"/>
-
         <Preference
             android:fragment="com.android.settings.accessibility.MagnificationPreferenceFragment"
             android:key="magnification_preference_screen"