Support for apiextensions.k8s.io/v1

[vivekzhere]

In Kubernetes v1.16 the apiextensions.k8s.io/v1beta1 is being marked as deprecated and due to be removed in Kubernetes v1.19:
https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.16.md#deprecations-and-removals

kubernetes-client/javascript added support for apiextensions.k8s.io/v1 from v0.12.0.
kubernetes-client/javascript#438