Add support for Scala Native

[ekrich]

This adds support for Scala Native and Scala 3.0.0-RC2 for both JVM and JS.

There may be a few things that need to be touched up as I am not super knowledgeable about the build and CI process.

[johnynek]

Thanks for doing this!

It looks like the CI is still building for M2 and M3, I think we can probably ditch those and move to only doing RC2 IMO.

Also, the ci yaml I think is generated with githubWorkflowGenerate.

Let me know if running that sbt task fixes things.

Thanks again for the PR. I look forward to merging.

[ekrich]

I think I figured it out. It looks like most repos were just moving from RC1 to RC2 with point releases.

We are needing this for scalameta/metaconfig so we can do a Scala Native scalafmt. I long time dream of ours.

Looks like a mima issue? scoverage?

[johnynek]

so, there are three things here:

1. move to 2.12.13
2. add 3.0.0-RC2
3. add scala-native

Can we maybe do the minimal thing you need? Maybe just add scala-native, or add scala native and RC2? Can that side-step the issue here:

scoverage/sbt-scoverage#319

[ekrich]

There is relentless upgrading going on. The easiest was to get the latest things but I may be able to back off some things. It is late here and I am pretty tired so I will try later this weekend. This is why the 2.12.13 is needed.
Error downloading org.scala-native:nscplugin_2.12.12:0.4.0

[johnynek]

scalacenter should fork and adopt scoverage.

[ekrich]

Scala Steward is your friend too.

[ekrich]

Now we are really hosed - tut-plugin.

[johnynek]

I guess we need to move to mdoc, added #339

[johnynek]

Now that #339 is closed by #340 can you merge master and see if we can keep the doc compiling?

[johnynek]

Okay...

I guess disabling coverage is worth it to support scala native since we rarely change the code these days anyway.

Thanks for the PR!

[ekrich]

Thank-you. It seems people have been waiting on the coverage plugin for awhile and this will really help us downstream.

[larsrh]

0.4.1 released with Scala Native support

[johnynek]

Thank you!