Json schema for message protocol

[aslakhellesoy]

This is a Draft PR to replace protobuf with pure JSON and JSON Schema, addressing #1386.

TODO:

• TypeScript: Modify ts code generator to define a Status alternate type from the enum in the schema. Same for ContentEncoding
• Working PR for cucumber-js
• Working PR for cucumber-ruby
• Working PR for cucumber-jvm

Later:

• Validate all generated messages in compatibility kit with the JSON schema.
• Elixir implementation/code generator
• .NET implementation/code generator
• Go implementation/code generator

We can live with a combination of protobuf/json schema implementations for some time, as long as we keep them in sync. The gherkin acceptance tests will catch any inconsistencies.

[WannesFransen1994]

Not sure if it's relevant, but following libraries might be helpful for the Elixir code generation:

• https://hex.pm/packages/ex_json_schema
• https://hex.pm/packages/json_schema
• https://hex.pm/packages/typed_struct

[aslakhellesoy]

Thanks @WannesFransen1994 we'll have a look at those.

[aurelien-reeves]

The removal of "sudo" before installing npm globally was the thing to fix the CI? 😨

This is a big PR to review. Here's a big list of question 😅

• What should we focus on while reviewing?
• What are the next steps?
• When could it be merged?
• Should we wait for the PR in cucumber-js, cucumber-ruby and cucumber-jvm to be ready too?
• Should we wait for .Net and Elixir to be implemented?

[aslakhellesoy]

The removal of "sudo" before installing npm globally was the thing to fix the CI? 😨

This is a big PR to review. Here's a big list of question 😅

• What should we focus on while reviewing?

Primarily finding breaking changes in APIs and data structures and update changelogs

• What are the next steps?

Merge to master and continue working on Cucumber PRs

• When could it be merged?

I think we can merge now, unless there are objections.

• Should we wait for the PR in cucumber-js, cucumber-ruby and cucumber-jvm to be ready too?

I think we can work on those after this is merged.

• Should we wait for .Net and Elixir to be implemented?

And Perl. I think we should disable them all (they already are). Waiting for them will cause too much delay. They can catch up at their own pace. We should create an issue for all 3 of them.