Allow driver code to set printed argument list in generated hpp

[WardBrian]

Submission Checklist

• Run unit tests
• Documentation
  • OR, no user-facing changes were made

Release notes

The generated model_compile_info will now feature arguments passed in from stancjs

Copyright and Licensing

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the BSD 3-clause license (https://opensource.org/licenses/BSD-3-Clause)

[WardBrian]

I’d like to write a good test for this before merging, I eyeballed that it looks correct

[hsbadr]

@WardBrian This does print the flags in the compile info:

  inline std::vector<std::string> model_compile_info() const noexcept {
    return std::vector<std::string>{"stanc_version = stanc3 v2.30.0-37-g09a0377", "stancflags = O1"};
  }

It might be useful to add them with the version comment too:

// Code generated by stanc v2.30.0-37-g09a0377

[hsbadr]

@WardBrian Would it make sense to unify how the flags are printed? For example, stanc binary gets stancflags = --O1 while the JS generates stancflags = O1. Alternatively, you may mention that it's command line or JS in the model compile info.

[WardBrian]

@rok-cesnovar should be ready now. I would also like to include this in the patch release

[rok-cesnovar]

Great, thanks!