sesame2spiner refactor

[adamdempsey90]

PR Summary

This does some refactoring on the code base to build sesame2spiner as a library that singularity-eos links in while maintaining the executable sesame2spiner. sesame2spiner was linking in singularity-eos for some things, so I have moved those shared headers into a new library called singularity-utils. For backwards compatibility in downstream codes, I have replaced the headers lost in singularity-eos/base with forwarding headers to singularity-utils. I have updated the includes in singularity-eos proper with the new ones.

If I did everything correctly, nothing should've changed. So my plan is to have this MR merged, then follow up with adding the functions to sesame2spiner the library to process tables without reading a file.

PR Checklist

• Adds a test for any bugs fixed. Adds tests for new features.
• Format your changes by using the make format command after configuring with cmake.
• Document any new features, update documentation for changes made.
• Make sure the copyright notice on any files you modified is up to date.
• After creating a pull request, note it in the CHANGELOG.md file.
• LANL employees: make sure tests pass both on the github CI and on the Darwin CI
• If ML was used, make sure to add a disclaimer at the top of a file indicating ML was used to assist in generating the file.
• If Agentic AI was used, have the AI generate a "proposed changes" markdown file and store it in the plan_histories folder, with a filename the same as the MR number.

If preparing for a new release, in addition please check the following:

• Update the version in cmake.
• Move the changes in the CHANGELOG.md file under a new header for the new release, and reset the categories.
• Maintainers: ensure spackages are up to date:
  • LANL-internal team, update XCAP spackages
  • Current maintainer of upstream spackages, submit MR to spack

[adamdempsey90]

Evidently there's some cmake stuff left to figure it when things like spiner are not requested or when not in submodule mode maybe