Investigate cluster adoption

[salasberryfin]

Description

Cluster adoption is a topic that has been brought up a few times over the last few weeks. Although this is provider-dependent, it would be interesting to test how this works and understand what are the pros/cons of performing this operation.

As a user, I'd like to convert an existing cluster into a CAPI cluster.

Notes

• CAPZ supports adopting AKS clusters: https://capz.sigs.k8s.io/managed/adopting-clusters