fix: Julia packaging issues

[LecrisUT]

Trying to fix JuliaPackaging/Yggdrasil#7310, and do a bit of cleanup.

• Added missing include(GoogleTest). It is surprising that this issue was not picked up by any other CI/downstream
• Moved compilation warnings to only CI. Downstream is getting bombarded with warnings that are slow to fix and it makes it hard to debug on their side.
• _Thread_local is not detected in Julia's packaging CI compiler issue on their end

@singularitti I will try to make some quick fixes here, but can you create the patches and try them on the Julia side CI?

After this we'll need to cherry-pick this one and add them to release-2.1 hotfix branch

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b02dedb) 83.80% compared to head (de9247c) 83.80%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #341   +/-   ##
========================================
  Coverage    83.80%   83.80%           
========================================
  Files           24       24           
  Lines         8167     8167           
========================================
  Hits          6844     6844           
  Misses        1323     1323           

Flag	Coverage Δ
c_api	77.18% <ø> (ø)
fortran_api	56.19% <ø> (ø)
python_api	80.47% <ø> (ø)
unit_tests	1.24% <ø> (ø)

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[singularitti]

Hi @LecrisUT, when you say the "packaging issue is fixed", do you mean the tests can be run? Because I still cannot run these tests when building Spglib artifacts on Julia CI systems.

[LecrisUT]

@singularitti Yes, the packaging of Gtest itself should be fixed here, so it should more reliably pick it up. The issue you've encountered in JuliaPackaging/Yggdrasil@189ff1b is that there were no pre-downloaded sources of gtest.

The main issue as downstream put it is to do the tests in an emulated environment. I have an idea (#363) that would be useful for conda as well, where it can run the packaged versions on the real machine. Not sure about Julia CI if it can have a similar feature.