java: Rewrite Groovy code generation to Java

[mpkorstanje]

🤔 What's the problem you've observed?

The Java module generates the list of CI systems using a Groovy script.

Unfortunately the groovy-maven-plugin doesn't support Java 17 source code yet (groovy/gmaven#28). While we currently only have to run on Java 17 for cucumber/cucumber-jvm#2644 it is not unimaginable that at some point in the future we'll also want to compile our own source code with 17 as well.

✨ Do you have a proposal for making it better?

With the increased release cadence of Java it would be prudent to keep the technology stack shallow and remove the dependency on Groovy and Groovy related components al together. So replacing the whole stack with pure Java would be beneficial.

📚 Any additional context?

This can effectively be solved in the same way as cucumber/cucumber-jvm#2648.