Track not implemented core features

[krzema12]

Best if it's done automatically or semi-automatically.

For example, I thought of getting a schema of what the workflow YAML can contain (here's one maintained by the community: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/github-workflow.json) and have a test suite that would produce various valid YAMLs with the library. Then, they would be fed to the schema one by one and the schema could somehow report which branches of it got activated. As the last step, covered branches from all tests could be merged into a single visualization, giving us something like a coverage of features given in a visually appealing way.

Extra points for analyzing usage frequency of each feature and producing a list of priorities what to implement :smile:

[krzema12]

See https://kotlinlang.slack.com/archives/C02UUATR7RC/p1657741431585289?thread_ts=1657740684.358839&cid=C02UUATR7RC

Try https://github.com/pwall567/json-kotlin-schema-codegen

[krzema12]

In the simplest form, let's just have a piece of docs tracking GitHub feature coverage, maintained manually. https://kotlinlang.slack.com/archives/C02UUATR7RC/p1682750778485959

[krzema12]

Basic feature coverage list has been added. Let's resolve it for now and see how it works.