[elixir] Convert proto-based messages to json schema based messages

[aurelien-reeves]

Originally submitted by @WannesFransen1994 on the monorepo as the following PR: cucumber/common#1952

It is intended to remove protobuf from the elixir implementation and to use the json schemas instead.

For the whole history, please see the original PR

[aurelien-reeves]

@WannesFransen1994 there are a few changes in that dedicated repo:

• Makefiles are used only for code generation - not for build anymore
• The CI is using github actions
  • one workflow per implementation: we will need a new one for elixir here: .github/workflows/test-elixir.yml
  • there is a dedicated workflow to make sure the generated code in the repo is up-to-date with the schemas

[aurelien-reeves]

I've worked a little bit on that to comply with the new repo

What is left to do I guess is to add tests?
Using the CCK could maybe be done like perl does?

[mpkorstanje]

@WannesFransen1994 for the CCK discussion #110

[luke-hill]

Hi @WannesFransen1994 - Is there any updates on this?

[mattwynne]

@WannesFransen1994 I am now working in Elixir day-to-day and although I'm still climbing the learning curve I'd certainly be been to pair with you on this if you have any time.

[mpkorstanje]

@mattwynne @luke-hill from what I understood and vaguely remember, Wannes work was subsidized and motivated by a grant. That grant has since run out. So I would not expect any more work to be done. I would ofcourse be pleasantly surprised otherwise.