Add helm hooks for admission controller deplolyment

[mlladb]

I've tested the following fix for the further issue described in Issue 25 at it works as expected. I don't think there are any likely issues to appear due to this change.

[eminaktas]

@mlladb Thanks for the PR. We want to reject DNSClass object if the validation fails. If we do this, we would skip that process.

I think we should add a DNSClass template inside the existing template and applying it with a hook so that it gets applied last. Would you be interested in contributing a commit for this feature?

[mlladb]

I've add the dnsclass templating. It seems to work as expected for me.
I can add my own custom config with the flowing values.yaml file.

kubedns-shepherd:
  certmanager:
    enabled: false
  dnsclass:
    allowedNamespaces:
      - default
      - kubedns-shepherd
    disabledNamespaces:
      - kube-system
    allowedDNSPolicies:
      - None
      - ClusterFirst
      - ClusterFirstWithHostNet
    dnsPolicy: None
    dnsConfig:
      nameservers:
        - 172.20.0.10
      searches:
        - "{{ .podNamespace }}.svc.cluster.local"
        - "svc.cluster.local"
        - "cluster.local"
      options: 
        - name: ndots
          value: "3"
        - name: edns0

[eminaktas]

Thank you for your contribution and validation—it’s highly appreciated. I’ve made a few suggestions. Please review them.

[eminaktas]

I also realized that your changes would work for Argo but when Helm applies the changes it will fail because it requires to wait the pods to be ready. I will include your changes and improve it. Thanks for your support.

[eminaktas]

LGTM!