Enable publishing snapshots using central portal

[rnc]

This is for https://central.sonatype.org/news/20250326_ossrh_sunset and also enables publishing snapshots following https://central.sonatype.org/publish/publish-portal-maven/

This will require the repository to be migrated to the new central portal system.

Secondly it will require two secrets added to the repository ( https://docs.github.com/en/actions/security-for-github-actions/security-guides/using-secrets-in-github-actions#creating-secrets-for-a-repository ) from the tokens generated in https://central.sonatype.org/publish/generate-portal-token named for SONATYPE_USERNAME and SONATYPE_PASSWORD to enable successful snapshot publishing.

[ctron]

This would run as part of the Eclipse configured repository. I'm not up to date with Maven publishing here. Would that work?

[rnc]

What are you referring to by This would run as part of the Eclipse configured repository ?
This PR relies on the new central portal publishing mechanisms but it assumes that migration has been done for this namespace (org.eclipse.packager ).

[ctron]

This repository is managed by the eclipse foundation. There used to be certain ways to publish to maven central. Managed by the foundation as well. I'd need to check documentation to see what the current state of this is.

[rnc]

This repository is managed by the eclipse foundation. There used to be certain ways to publish to maven central. Managed by the foundation as well. I'd need to check documentation to see what the current state of this is.

Ok, maybe in that case this PR isn't applicable. I'd be interested in any links to the documentation.

[ctron]

The first link which comes into my mind is: https://eclipse-cbi.github.io/cbi-website/

Alternatively: https://chat.eclipse.org/#/welcome

[rnc]

The first link which comes into my mind is: eclipse-cbi.github.io/cbi-website

Alternatively: chat.eclipse.org#/welcome

Looking through the first link they reference a different Nexus server (https://repo.eclipse.org/) ; but packager appears to be deployed to Central (https://repo1.maven.org/maven2/org/eclipse/packager/packager/) so I am confused as to how you set it up. Can you clarify the setup and if this PR isn't needed release a new version anyway please? (for the rpm-builder PR)