CI: Publish `Docker` images for all server services and multiple architectures

[hpoeche]

With #407 the server gained the Registry and Discovery services, which leads to three different Docker images (one for each service Registry, Discovery, Repository).

We need to adapt the release.yml workflow in order to publish all three services to Dockerhub.
Additionally the images should be build as multi-platform images, that support amd64 and arm architecture.