Upload distributions to GitHub releases

[jponge]

• Check if we can use CI to deploy the latest build as a distribution
• Releases should be uploaded manually so we can craft a release with proper release notes, etc.

[jponge]

I've added workflow steps to upload a distribution as a workflow artifact on every build, then a nightly cleanup action to remove those older than 14 days.

[jponge]

Note I need to contact Eclipse because I cannot set secrets for CI, etc.