do not emit jar files for the legacy artifacts

[hamzaremmal]

In this PR, we stop emitting jar files for all scala3-library and scala3-libary_sjs.
These projects do not have any content and only serve to evict projects that depend on an older versions of them to the new artifacts.

[sjrd]

Do we have evidence that this reliably works with all build tools? Aren't they going to get confused by resolving an artifact that does not provide any jar? Is this something that people do in the broader ecosystem?

[hamzaremmal]

Do we have evidence that this reliably works with all build tools? Aren't they going to get confused by resolving an artifact that does not provide any jar? Is this something that people do in the broader ecosystem?

mill and scala-cli work fine. maven should work because it knows what a pom artifact is and I would be surprised if it doesn't. Only sbt fails and complains about the missing jar. sbt should be updated to not hardcode looking for the scala3_library jar.

[sjrd]

I don't know. It doesn't seem to be a thing in the Maven ecosystem. We shouldn't go against established practices of Maven packages. That way only lies problems. Even if we're lucky now, who's to say someone won't have an entreprise proxy that complains about this? It's not worth it.

[SethTisue]

@eed3si9n fyi this is still under consideration