Add new string for audio switcher

    <!-- Title for media output settings -->

    <string name="media_output_title">Play media to</string>

    <!-- Summary for media output default settings. (this device) [CHAR LIMIT=30] -->

    <string name="media_output_default_summary">This device</string>

    <!-- Summary for media output settings. (phone) -->

    <string name="media_output_summary" product="default">Phone</string>