Add functionality for Spack module to take data runners

[nick-stroud]

data_files are a subset of startup-script.runners. They can only be of type data and must have a destination of an absolute path. While this same functionality could be achieved by using startup script directly, it was decided that it would be logically cleaner to define all of the spack configs in a single module.

It was decided to not duplicate the validation that startup script does. This leaves some minor naming mismatch in error messages as validation will report that "runner cannot do such and such" instead of "data_files".

Tested manually: Upload file via data runner and then cat the file in commands

Submission Checklist

Please take the following actions before submitting this pull request.

• Fork your PR branch from the Toolkit "develop" branch (not main)
• Test all changes with pre-commit in a local branch #
• Confirm that "make tests" passes all tests
• Add or modify unit tests to cover code changes
• Ensure that unit test coverage remains above 80%
• Update all applicable documentation
• Follow Cloud HPC Toolkit Contribution guidelines #

[tpdownes]

Effectively, I believe sources must be absolute until we support a mechanism for staging data into the deployment directory. It's a "Toolkit limit" and not a bar I expect this PR to clear. I like that it also content, at least for text files.

Please make the change I request and merge.