Add display session checks to the system info report

Gather additional information regarding the display server. This makes it easier to spot issues on end users setup and it will allow developers differentiate X11 to Wayland sessions.

Checking if a session is using Wayland is not trivial, because the common environment variable WAYLAND_DISPLAY is not necessarily a requirement. If unset, Wayland will also fallback to its default wayland-0 socket. So we need to check if the Wayland socket actually exists, rather than just looking up to the WAYLAND_DISPLAY env var.