Support IPv6 on service CIDR

[olljanat]

First step to solve #18

Add logic to detect if cluster does not have support for IPv4 or if vcluster is forced to use IPv6 only with policy engine.

At least combination of dual stack cluster with Kyverno policy like this:

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: service-ipv6-only
spec:
  validationFailureAction: enforce
  background: false
  rules:
  - name: service-ipv6-only
    match:
      resources:
        kinds:
        - Service
        namespaces:
        - "vcluster-*"
    preconditions:
      all:
      - key: "{{request.operation}}"
        operator: In
        value:
        - CREATE
    mutate:
      patchStrategicMerge:
        spec:
          ipFamilyPolicy: SingleStack
          ipFamilies:
          - IPv6

and using --distro k8s works.

Pure IPv6 only env where also host cluster is IPv6 only will need more work. K0s needs this PR k0sproject/k0s#1292 and K3s needs this PR k3s-io/k3s#4450 before those can be used with this one.

[FabianKramm]

@olljanat thanks for creating this PR! LGTM!