Declare CAST_SETTINGS activity.

Currently this is the same as the WIFI_DISPLAY_SETTINGS activity
although we may eventually split them apart.

Change-Id: I4c4482792abc3d3d22fb50ee9657b536374a618f

AndroidManifest.xml

@@ -1449,6 +1449,7 @@
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <action android:name="android.settings.WIFI_DISPLAY_SETTINGS" />
+                <action android:name="android.settings.CAST_SETTINGS" />
                 <category android:name="android.intent.category.DEFAULT" />
             </intent-filter>
             <meta-data android:name="com.android.settings.FRAGMENT_CLASS"