Add switch preference for Audio Description.

Preview: https://screenshot.googleplex.com/AXMFpGPPGPPBzXG

Bug: 214634651i
Test: Local flash and test
Test: atest SettingsRoboTests:AudioDescriptionPreferenceControllerTest

Change-Id: Ice2e2bc8ec4e77aba0cd486f854254009b91e541

color-check-baseline.xml

@@ -2877,6 +2877,22 @@
             column="13"/>
     </issue>
 
+    <issue
+        id="HardCodedColor"
+        severity="Error"
+        message="Avoid using hardcoded color"
+        category="Correctness"
+        priority="4"
+        summary="Using hardcoded color"
+        explanation="Hardcoded color values are bad because theme changes cannot be uniformly applied.Instead use the theme specific colors such as `?android:attr/textColorPrimary` in attributes.&#xA;This ensures that a theme change from a light to a dark theme can be uniformlyapplied across the app."
+        errorLine1="            android:color=&quot;@color/accessibility_feature_background&quot;/>"
+        errorLine2="            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
+        <location
+            file="res/drawable/ic_audio_description.xml"
+            line="22"
+            column="13"/>
+    </issue>
+
     <issue
         id="HardCodedColor"
         severity="Error"