Support Publishing via the Central Portal instead of legacy OSSRH

[peteraraujo]

Sonatype changed their publishing method for new artifacts and now it has to be done via the Central Portal. On their website, it says that there is no official Gradle plugin yet but that we can use JReleaser, which does support the new method.,

[ILIYANGERMANOV]

+1

[ZivStep]

+1

[ILIYANGERMANOV]

Fyi: I managed to fix it in https://github.com/Ivy-Apps/di

A few notes:

• key-id must be only the last 8 chars
• the key must be uploaded on a keyserver and its email verified

[pahill]

We have completely overhauled this and are addressing the issue now.

[atsushieno]

Can we see a proof of working publication on GitHub Actions ("Publish" workflow) ? I'm asking, because I keep failing to get it working, even with minimum changes from this template. For example: https://github.com/atsushieno/multiplatform-library-template-nexus-publisher/actions/runs/14990100091/job/42111980379

I'm seeing no attempt to actually run this workflow at https://github.com/Kotlin/multiplatform-library-template/actions/workflows/publish.yml .

[atsushieno]

I fixed ^ in this PR: #48