Bring Argon up-to-date (GHC 9.10)

[ozkutuk]

This PR overhauls the entire project so that it compiles with modern GHC versions. Most notable changes are:

• Migration from haskell-src-exts to ghc-lib-parser (Thereby supporting up to GHC 9.10)
• Migration from several unmaintained libraries to their modern alternatives:
  • docopt → optparse-applicative
  • lens-simple → microlens
  • dirstream → Glob
  • quite a few more
• Replace Travis CI config with GitHub Actions
• Introduce a formatter, a development environment based on Nix, and several other nicities for developers
• ...and all around cleanup

[kqr]

Ah, nuts. I saw this PR only after I had submitted #41 .

[ozkutuk]

@kqr At the time before opening the PR, I actually have got in touch with the author through email, basically asking if they would be willing to merge a PR of this scope if I were to create it. They responded positively, but also stated that they lately have very little time for OSS maintenance (which probably explains why they never actually merged the PR). I have also considered forking the project, but since I am not a regular user of Argon (or a user at all really), I have no interest in maintaining a fork, hence I refrained from doing so.
All that is to say, I don't feel attached to my PR. It was intended to be a one-time contribution to keep the project alive. If you are a regular user of Argon, you might be better off maintaining your own fork, and in that case you can use this PR as a jumping off point if you wish, or rather take the more conservative approach like you did with your own PR. In any case, I would be totally okay with closing this PR if you do manage to get yours merged.

[kqr]

Well, I'm in practically the same situation as you. I wanted to play around with Argon for a bit to learn more about a codebase through that lens, but I don't plan on using it regularly. I was just hoping to get a small update in to hackage and nixpkgs so people don't bounce off it like I almost did!