Add toggle for enabling/diabling mobile data

Bug: 117229760
Test: Build, Robolectric
Change-Id: I04b92b1f36e3fe92fb92851b2ed17e3cd7dcefb8
diff --git a/res/xml/mobile_network_fragment.xml b/res/xml/mobile_network_fragment.xml
index 77253a7..675ecb0 100644
--- a/res/xml/mobile_network_fragment.xml
+++ b/res/xml/mobile_network_fragment.xml
@@ -17,4 +17,11 @@
 
 <PreferenceScreen
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:title="@string/mobile_network_settings"/>
+    xmlns:settings="http://schemas.android.com/apk/res-auto"
+    android:title="@string/mobile_network_settings">
+    <SwitchPreference
+        android:key="@string/pk_mobile_data_toggle"
+        android:summary="@string/mobile_network_toggle_summary"
+        android:title="@string/mobile_network_toggle_title"
+        settings:controller="com.android.car.settings.network.MobileDataTogglePreferenceController"/>
+</PreferenceScreen>