Nix files for workadventure

this is based on the original packages by SuperSandro2000 and parts of the fediventure monorepo.

The intended usage is to import this into your config and then use it as a normal NixOS service, i.e. like so:

{config, pkgs, ...}: {
  imports = [ "${this-repo}/workadventure.nix" ];

  services.workadventure."localhost" = {
    nginx = {
      default = true;
      domain = "localhost";
    };

    frontend.startRoomUrl = "/_/global/localhost/maps/main.json";      
    commonConfig = {
      webrtc.stun.url = "stun:coturn.somewhere:3478";
      webrtc.turn = {
        url = "turn:coturn.somewhere";
        user = "turn";
        password = "TURN_PASSWORD";
      };
      jitsi.url = "meet.somewhere.net";
    };
  };
}