Write GitHub Actions workflow files in Kotlin instead of YAML

[Vampire]

For now a 1:1 translation from previous Yaml.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.79%. Comparing base (2c7db77) to head (5d5dfdd).
Report is 177 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1630      +/-   ##
============================================
+ Coverage     80.44%   81.79%   +1.34%     
- Complexity     4337     4642     +305     
============================================
  Files           441      450       +9     
  Lines         13534    14582    +1048     
  Branches       1707     1839     +132     
============================================
+ Hits          10888    11927    +1039     
+ Misses         2008     1975      -33     
- Partials        638      680      +42     

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[Vampire]

Well, almost 1:1, I added some names where only IDs were present. Due to that the required checks now do not match anymore as they are considering the name, not the ID.

[leonard84]

Not seeing the advantages yet.

[leonard84]

Can we keep the .yml extension for the generated files, so that we can actually see the diff?

[Vampire]

Yes, you can manually configure the target file name.
I changed it to ...yml, but maybe we want to return to the default after you verified the changes to not have the unnecessary configuration?

[Vampire]

Not seeing the advantages yet.

Well, noone really likes reading or writing YAML. :-D
And especially with such a complex DSL like GitHub workflow files.
You always have to read how you can do what where how and have to trial and error.
By using this library, you have a proper type-safe DSL with IntelliSense in the IDE that makes it nice to write and read GHA workflows.

You can also easily reuse common logic as you have a turing-complete language at hand.
So for example the logic in the custom local setup-build-env and setup-jdks workflows could just be done in a common Kotlin script, if one would be used (read above for why none is used so far).

You could then for example also centrally define the variants and Java versions, or even the complete test matrix and reuse it.

And where it also comes in handy is, for the changes in #1629 as there I can then easily change the script to calculate the size of the Matrix and set the after_n_builds accordingly without the risk of forgetting to update it.

[Vampire]

I now added another commit, that leverages the fact we have a programming language at hand and uses it for the variants and java versions handling, that also shows that it is really useful. :-)

[Vampire]

And another commit added, so that the build script and the workflow generation script use one common source for the Java versions and variants. :-)

I think I'm out of improvement ideas for now, so review-on. :-)

[leonard84]

By using this library, you have a proper type-safe DSL with IntelliSense in the IDE that makes it nice to write and read GHA workflows.

Unless, it is not supported, then you end up with _customArguments and unsightly mapOf, which read much worse through all the added noise IMHO.