Enabling Gitlab Package registry

Summary

We will enable GitLab Package Registry to allow using GitLab as a public registry for a variety of supported package managers.

This will be a staged roll-out. After internal tests, we will invite interested Eclipse projects to help us fine-tune the configuration and provide feedback before we roll it out to all Eclipse projects hosted on https://gitlab.eclipse.org.

• To avoid exploding disk usage consumption, we need to consider a reasonable retention policy and automatic clean-up strategy.
• We will compare the GitLab Package Registry with other external package registries and look for the best fitting solution for the Eclipse community.

This issue will track the progress.

• internal tests
• Limited test
• General availability (GA)