1.39 - WSLg II: WSLg Better

• Handle the WSLg X11 socket and runtime directory better, following Daniel Llewellyn's example here: https://github.com/diddledan/one-script-wsl2-systemd

NOTE: The Fedora and Arch installers require manually enabling the wslg-xwayland.socket systemd unit on first launch.