Publish container nextjs images to ghcr.io/radiorabe

[hairmare]

RaBe currently uses ghcr.io/radiorabe as default registry, we want to publish the nextjs image there.

As a rule of thumb, we expect images on our registry to be automatically built and pushed using the shared container image actions. This ensures that the images are labeled properly for ghcr, and also supports clean builds and security scanning out of the box.

[hairmare]

@AareFabrik I created this issue and it's parent after iTinu let me know that you are looking for our container registry.

The linked pull-request implements our default pipeline for the nextjs image.