New function print_stan_file() for color formatted Stan code in quarto and R markdown

[avehtari]

closes #1149

• print_stan_file() is a helper function to make it easier to have color formatted Stan code in Quarto documents, especially when the Stan code is in a file.
• In addition write_stan_file() was moved to file.R

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):

Aki Vehtari

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 97.43590% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.87%. Comparing base (5809552) to head (ed63153).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
R/file.R	97.43%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1166      +/-   ##
==========================================
+ Coverage   90.85%   90.87%   +0.02%     
==========================================
  Files          14       15       +1     
  Lines        5924     5938      +14     
==========================================
+ Hits         5382     5396      +14     
  Misses        542      542              

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[jgabry]

Thanks, looks like it's passing now. We can ignore the one Mac failure, there's an unrelated issue with r-devel right now.

[jgabry]

Thanks, looks like it's passing now. We can ignore the one Mac failure, there's an unrelated issue with r-devel right now.

Actually there's a failure on windows when we use an older windows and R setup. I think it's because of the version of testthat that is used isn't compatible with some of the testthat code used in the new tests. I think I know how to fix it.

[jgabry]

Looks good. If my changes fixed the failing tests then we can merge this. If not then I'll look into it more.