Added airplay2 and dlna reception function

[Wanderingkang]

Feature request

Can you add the AirPlay2 and DLNA acceptance function, after the iOS or Android device is connected, it accepts data through AirPlay2, sends the data directly to the MPD, and the MPD is responsible for decoding and other operations, and after the AirPlay2 or DLNA device is connected, the sound of AirPlay2 or DLNA is played. In this way, the function may be more complete, not the MPD sends the sound to the airplay or DLNA, it is the airplay or DLNA that transmits the data to the MPD.
Source code reference：https://github.com/mikebrady/shairport-sync.git
Source code reference：https://github.com/hzeller/gmrender-resurrect.git

[MaxKellermann]

I have no interest in this feature, so this will only ever be implemented if there's a volunteer to submit code to MPD.