Possible tweak to rcac-foam-shell script

[lev]

The rcac-foam-shell script only binds /var/opt/ (and does not bind $XDG_RUNTIME_DIR or use any of the other logic that the rcac-foam-wrapper performs).

This works, for simple things like copying examples, but will break if the user tries to run any of the FOAM tools inside (especially GUI-based). While not intended, launching a container shell and then spawning FOAM tools from it (e.g. for interactive debugging) is not an entirely unreasonable workflow, so it'd be nice if we could support it.

Should be an easy win though: just make rcac-foam-shell an exact replica of rcac-foam-wrapper with the exception of the last line becoming

exec singularity shell "${SING_EXTRAS[@]}"  "$IMG"

[wu979]

I see. There is no GUI apps inside this particular container, but it is good to make rcac-foam-shell as general as possibile. Changes are made accordingly.