xdg-open dependency is not documented

From Henrik Nortamo via Mattermost (DestinE project):

There is an undocumented dependency on xdg-open which produces [CRITICAL] error when running autosubmit report. Safe to ignore and a pdf is actually produced to /plot/ so the message is a bit misleading

Maybe we can have a flag/toggle in the configuration for the launcher and maybe have a no-op launcher for when running in headless mode. Or maybe a flag to disable it, or a --headless option that can be used for the same reason.

I have confirmed the issue happens on 4.0-branch-2022 as well.

Code where it is used: https://earth.bsc.es/gitlab/search?search=xdg-open&nav_source=navbar&project_id=58&group_id=4&search_code=true&repository_ref=master