Setting up pipeline to push a container to registry

[j-i-l]

Goal

We want to have a basic pipeline setup that builds a container and publishes it in the container registry.

This issue is about setting up the pipeline and thus the actual configuration of the container is irrelevant in this context.

[j-i-l]

• official example
• working with the container registry
• general about publishing packages in gh
• offering gh actions based on dockers - might be of interest to us