Container registry rate-limit protection

Created by: matofeder

As a container registry administrator, I want to be able to set rate-limit protection to prevent DoS attacks (see docker-hub rate limit as an example).

Note that this feature is not available directly in the Harbor project, see open issue.

As the k8s-harbor project is intended to deploy Harbor into k8s cluster, the k8s ingress controller is probably the right place to achieve this kind of protection on Harbor.