Update list of admission plugins with a config file

roles/kubernetes/control-plane/vars/main.yaml

 ---
 # list of admission plugins that needs to be configured
+# https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/
 kube_apiserver_admission_plugins_needs_configuration:
 - EventRateLimit
+- ImagePolicyWebhook
 - PodSecurity
 - PodNodeSelector