add filesystem mount modules

[lastephey]

Add --home, --scratch, and --cfs mount modules to make mounting filesystems a little more straightforward for users.

[chrissamuel]

I was wondering if it might be better to have something like:

--mount-group=home,scratch,cfs

That way could be easier to extend site by site without changing the options available to users?

[lastephey]

Sure, that seems like a good idea.

[kellyrowland]

Opened #120 to add modules for various directories of interest.

@chrissamuel I don't think I quite understand the difference between what you've suggested and that any site using podman-hpc could add their own modules to mount file systems, directories, etc.

[danfulton]

There's nothing we're currently doing to enforce that other sites would implement modules with the same names/flags as us (e.g. --gpu). I think it might, sort of, be more future proof, but also adds some complexity (no other site specific flags currently take options).

It might be worth sitting down and discussing CLI choices at some point... what we have is more organic than designed.

[scanon]

See pull #120