Fix errors and add warnings with optical properties

[sethrj]

Split from #2303

• Add a warning when both RAYLEIGH (rayleigh scattering MFP) and COMPRESSIBILITY (alternative analytic MFP calculation) are present.
• Adds missing data to the DUNE cryostat test including RINDEX to the glass.
• Fix failure when an optical material doesn't have scintillation.
• Activate mucf import which wasn't being tested.
• Mark GPU generator tests as disabled when CUDA is turned off via the environment (CI)

[github-actions]

Test summary

 5 950 files   9 569 suites   21m 34s ⏱️
 2 210 tests  2 169 ✅  41 💤 0 ❌
32 866 runs  32 725 ✅ 141 💤 0 ❌

Results for commit 8a595b1.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.24%. Comparing base (cd0fd07) to head (8a595b1).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2306      +/-   ##
===========================================
+ Coverage    87.21%   87.24%   +0.03%     
===========================================
  Files         1357     1357              
  Lines        43253    43246       -7     
  Branches     13688    13189     -499     
===========================================
+ Hits         37723    37732       +9     
+ Misses        4492     4305     -187     
- Partials      1038     1209     +171     

Files with missing lines	Coverage Δ
src/celeritas/ext/detail/GeantPhysicsLoader.cc	95.13% <100.00%> (+2.79%)	⬆️
...leritas/optical/gen/detail/MatScintSpecInserter.hh	81.08% <100.00%> (-16.88%)	⬇️
src/geocel/GeantGdmlLoader.cc	84.93% <100.00%> (+0.20%)	⬆️

... and 113 files with indirect coverage changes

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[amandalund]

Thanks!