gen2 clusters don't support overrides (basecluster is cloned verbatim)

[bcle]

Today, in order to deploy a new workload cluster with minor tweaks to an existing base cluster, the base must be cloned into a new base, if the user doesn't want to affect existing workload clusters.

This results in duplication of the common characteristics. Consider a way for the user to specify small changes (possibly expressed as patches) to the base cluster, which are unique to the workload cluster, and will be preserved if and when the base cluster changes.

Aha! Link: https://pf9.aha.io/features/ARLON-129