base clusters don't support CAPI ClusterClass (and therefore CAPD quickstart example)

[bcle]

I discovered this while trying to create a workload cluster from a base cluster that was created from clusterctl generate with CAPD (CAPI for Docker) provider. The issue is: by default, that command generates a cluster that takes advantage of the ClusterClass resource, which is CAPI's experimental support for cluster templates, also called "topologies".

The top-level Cluster resource has several references to ClusterClass-like resources. But unfortunately, those don't use the traditional ref type of properties, instead, they use XXXTopologyXXX names. The current kustomize configuration is incapable of renaming fields of that kind, resulting in a broken workload cluster.

Aha! Link: https://pf9.aha.io/features/ARLON-296

[cruizen]

This is related to #222