Service exposition with ListenerClasses

The operator deploys a Listener for the Node pod. The listener defaults to only being accessible from within the Kubernetes cluster, but this can be changed by setting .spec.nodes.roleConfig.listenerClass:

spec:
  nodes:
    roleConfig:
      listenerClass: external-unstable  (1)

1	Specify one of `external-stable`, `external-unstable`, `cluster-internal` or a custom ListenerClass (the default setting is `cluster-internal`).