[Codegen] Refactor the Codegen

[luke-hill]

🤔 What's changed?

Change the codegen to be structured neatly and properly. Instead of just tacked into the jsonschema

It will live in its own TLD. It will also be split into the subsequent classes, cleaned up via rubocop and eventually neatened up to remove and redundancies / sub-optimisations.

NB: This isn't aimed to improve the codegen much. I know the way each language interprets the generated items is different. For now this is just aimed as a "1st Pass" at tidying up.

⚡️ What's your motivation?

Tidy up messages codebase. Improve Codegen so that we can read it and optimise it more down the line

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, etc. without changing behaviour)

♻️ Anything particular you want feedback on?

This can be thought of as an "Internal" Breaking change. But given no-one who is a consumer will see this breaking change (As all codegen code will be identical), it can go out as a patch release

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

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[luke-hill]

@clrudolphi this is about 85% complete at the moment. I've got 2 more batches of things to tidy up, but it's essentially almost done.

Again as mentioned if there's going to be a close time overlap, I'll hold off on merging this until you've got yours in that way I can fix up the conflicts my end.

[clrudolphi]

@luke-hill Thanks for the heads-up. I think we're done, just pending final reviews by @mpkorstanje and @gasparnagy
Will your work finish up in the next day or two? If not, I hope we will slip in ahead of you.

[luke-hill]

ping @gasparnagy / @clrudolphi - It might be worth considering at what "point" we want to announce the changes being made by yourselves such that I can change this comment (Or you can), to move it into the above bracket.

[gasparnagy]

I would say that until we don't have the json report gen ready, there might be smaller changes needed, so I would announce it after we have it ready on Reqnroll side.

[luke-hill]

Ping @clrudolphi - I've only made some minor changes to the dotNET stuff here, but if you want to check it out go ahead

[clrudolphi]

Ping @clrudolphi - I've only made some minor changes to the dotNET stuff here, but if you want to check it out go ahead

Looks good.