The crd-puller can be used for testing and development in order to export a
CustomResourceDefinition for any Group/Kind (GK) in a Kubernetes cluster.
The main difference between this and kcp's own crd-puller is that this one
works based on GKs and not resources (i.e. on apps/Deployment instead of
apps.deployments). This is more useful since a PublishedResource publishes a
specific Kind and version. Also, this puller pulls all available versions, not
just the preferred version.