Allow changing AirPlay and DLNA name

While typically speaking it’s quite useful that both the hostname and AirPlay and DLNA names are the same there are times where it would be better if the name for AirPlay and DLNA can be different from the hostname.
This is useful when the local domain is already descriptive enough that for example music.awesomeclub.local is perfectly fine but having the AirPlay endpoint being called “music” is not.