Migrate publishing snapshots from Jenkins to GitHub

[paullatzelsperger]

Feature Request

Publishing Maven artefacts is currently handled by Jenkins for both snapshot builds and release builds. GitHub actions simply triggered Jenkins via its API.

This pull request enables us to publish to OSSRH/MavenCentral directly from GH Actions.

Therefor, we should create a workflow in the .github repo, that can be re-used by every component, that publishes snapshot builds directly from GH Actions.

Note that scheduled builds (nightlies) or actual releases will remain with Jenkins for the time being.

Then, once the workflow has been created (and tested), we should update the trigger_snapshot.yaml workflow in every component to simply trigger this re-usable WF.

Which Areas Would Be Affected?

Snapshot builds

Why Is the Feature Desired?

Reducing system-to-system configuration, better integration with GH. Detailed rationale is found here.

Solution Proposal

outlined in this decision-record

once all the components are updated, we should remove the EF_USER and EF_TOKEN secrets using the .eclipsefdn repo

[github-actions]

Thanks for your contribution 🔥 We will take a look asap 🚀