Add a new top-level setting for car/desktop dock settings.
Sub menu contains one item - Audio (settings)
Sub text for Audio shows current docked status and launches either the
audio settings or a dialog saying that you're not docked and you need to
buy a new dock from Google (kidding).
The Settings app now shows a "Search settings" item,
if there is an activity that handles the Search settings intent.
This conditionally included settings is handled in the same way
as the sync settings.
