🌱 Add ClusterClass column to Cluster CRD

[sbueringer]

Signed-off-by: Stefan Büringer buringerst@vmware.com

What this PR does / why we need it:
Adds a ClusterClass column to the Cluster CRD. Super helpful to determine if a Cluster is a classy cluster, and if yes which ClusterClass it uses

k get clusterclass,cluster,kcp,md
NAME                                        AGE
clusterclass.cluster.x-k8s.io/quick-start   5m44s

NAME                                       CLUSTERCLASS   PHASE         AGE     VERSION
cluster.cluster.x-k8s.io/capi-quickstart                  Provisioned   5m50s
cluster.cluster.x-k8s.io/my-cluster        quick-start    Provisioned   5m41s   v1.26.0

NAME                                                                              CLUSTER           INITIALIZED   API SERVER AVAILABLE   REPLICAS   READY   UPDATED   UNAVAILABLE   AGE     VERSION
kubeadmcontrolplane.controlplane.cluster.x-k8s.io/capi-quickstart-control-plane   capi-quickstart   true                                 1                  1         1             5m50s   v1.25.0
kubeadmcontrolplane.controlplane.cluster.x-k8s.io/my-cluster-465k6                my-cluster        true                                 1                  1         1             5m41s   v1.26.0

NAME                                                                        CLUSTER           REPLICAS   READY   UPDATED   UNAVAILABLE   PHASE       AGE     VERSION
machinedeployment.cluster.x-k8s.io/capi-quickstart-md-0                     capi-quickstart   1                  1         1             ScalingUp   5m50s   v1.25.0
machinedeployment.cluster.x-k8s.io/my-cluster-default-worker-topo-1-qsrp5   my-cluster        1                  1         1             ScalingUp   5m40s   v1.26.0
machinedeployment.cluster.x-k8s.io/my-cluster-default-worker-topo-2-gx42r   my-cluster        1                  1         1             ScalingUp   5m40s   v1.26.0
machinedeployment.cluster.x-k8s.io/my-cluster-default-worker-topo-3-jmwvt   my-cluster        1                  1         1             ScalingUp   5m40s   v1.26.0

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[killianmuldoon]

/area api

(just barely)

[killianmuldoon]

/lgtm
/approve
/hold

Feel free to unhold - just in case anyone else wants to take a look as it's an API change.

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 250588dc8844c2aaacdef07428f470d01c01b95e

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: killianmuldoon

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[sbueringer]

Debatable if the columns of the CRD are an API :D

But let's not go there. Thx for the review, I'll keep it open for a few days, I'm not in a rush

[furkatgofurov7]

/lgtm

[killianmuldoon]

/hold cancel