Add the ability for vsphere ClusterPools to spread instances across failure domains. Unfortunately we need to address two paths:

• The install-config template, where we should hopefully get the new hotness for free
• ClusterPool.Spec.Platform.VSphere, which is shared with ClusterDeployment.Spec.Platform.VSphere, but isn't used for ClusterDeployments.

Consider deprecating the latter! I don't think we need it!