Support kubernetes ingress

[yonahd]

Find Kubernetes Ingresses that are not used. -> Not pointing to any services
The command should be ing or ingress

[Yuni-sa]

@yonahd, I can help with this.
what do you think about iterating over the rules and paths of an ingress and checking if the service (using path.Backend.Service.Name) exists?
makes it easy to find unused ingresses by checking if all of the services do not exist, also if one service exist you can skip the rest of the paths in the ingress.

side note: do we also need to check for resources (path.Backend.Resource)? you only pointed out about services.

[yonahd]

@Yuni-sa Sounds good!
If the the backend is a resource it should automatically be marked as used (we need to be safe)
A non prefixed ingress should be accounted for as well

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: test-ingress
spec:
  defaultBackend:
    service:
      name: test
      port:
        number: 80

[yonahd]

Looking at it this way, it is a pretty large pr.
If you want someone to take this together with you it should be an option