Support multiple simultaneous VNC clients to connect to a session

On Ubuntu 20.04 using Vino, I was able to connect multiple VNC clients simultaneously to my server. With the move to gnome-remote-desktop and using Wayland, trying to connect to my server with a VNC client fails if there is already another VNC client connected from a different machine. This makes is impossible to access my server graphically if I've left an active VNC connection on another device and can't access that device now.

As the bare minimum, if a new VNC connection would disconnect the older ongoing connection, it's still better than the current scenario.