Refactoring docker ingress annotations

[renesch-de]

The annotations in the 'ingress' section are not used anymore for docker ingress objects. They are now part of an Values.nexus.docker.registries entry. With this change its now possible to define annotations on a docker registry level. This is helpfull if annotations like external-dns.alpha.kubernetes.io/hostname must be used, where each hostname is distinct for each ingress object created.

[renesch-de]

At the moment this is a simple refactoring by separating the annotations for the UI and the Docker-Registry ingress objects. In future, it would be even better to refactor the ingress annotation handling in general, so that the following is possible:

• Support the definition of common annotations that are applied to all ingress objects that the chart creates.
• Support the definition of additional annotations for just the UI/Docker-Subdomain ingress object.
• Support the definition of additional common annotations for all Docker-Registry ingress objects.
• Support the definition of additional annotations for a specific Docker-Registry ingress object.