gherkin/java: Use generated code instead of reading gherkin-languages.json

[mpkorstanje]

🤔 What's the problem you're trying to solve?

Reading gherkin-languages.json requires the inclusion of a json library. To avoid poluting the class path this library has to be shaded. This makes in place upgrades (e.g. for security reasons) harder.

✨ What's your proposed solution?

Instead of reading gherkin-languages.json generate the code for a list of GherkinDialect objects. See for example https://github.com/cucumber/ci-environment/blob/cfedf95c90052b2db812a56851daf1a6f7d1f690/java/src/main/groovy/io/cucumber/cienvironment/CiEnvironments.gsp#L7-L13