`fpm`ize PRIMA

[perazz]

First off, congratulations and thank you on modernizing and improving a great optimization library.

With this ticket, I would like to suggest that PRIMA is integrated with the Fortran Package Manager ecosystem. This would have tremendous benefits for the Modern Fortran community.

From what I see, there are no pre-processing steps involved: to enable PRIMA to be used with fpm, all that's needed is just a refactoring of the folder structure.

One easy way to achieve that would be to have a GitHub CI automation doing that with a script, and deploying to a separate branch of the PRIMA repository, similar to what the Fortran Standard Library does.