Only copy include files (compiler, module choice) that are used

[climbfuji]

Description

Update spack-ext/lib/spack-stack/stack/stack_env.py to only copy the include files (compiler, module choice) that are used from the common/site config directories to the environment's common/site directories.

This PR is optional. If folks prefer to copy everything, that's fine with me. I find it less confusing to not have yaml config files in the environment common/site directories that aren't used.

Dependencies

None

Issues addressed

Closes #2069

Applications affected

None

Systems affected

None

Testing

• CI: Note whether the automatic tests (GitHub actions tests that run automatically for every commit) pass or not
  • GitHub actions CI tests pass
  • GitHub actions CI tests do not pass (provide explanation)
  • GitHub actions CI tests skipped (provide explanation if necessary)
• New tests added: List and describe any new tests added to GitHub actions
  • ...
• Additional testing: Add information on any additional tests conducted
  • Tested spack stack create env ... and verified that only the files are copied that are used by the environment

Checklist

• This PR addresses one issue/problem/enhancement or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.
• All necessary updates to the documentation (spack-stack wiki) will be made when this PR is merged

[AlexanderRichert-NOAA]

FWIW I could see it being useful to also have a flag for copying other files/directories to support misc. site-specific stuff, but that can be added later. This is definitely a positive change.

[climbfuji]

I'll merge this after #2140 without rerunning the tests.