Support `kubectl scale` and the /scale subresource

[tnozicka]

Is this a bug report or feature request?

• Feature Request

What should the feature do:

# kubectl get scyllacluster/basic
NAME    AGE
basic   3m57s

# kubectl scale scyllacluster/basic --replicas=3
Error from server (NotFound): scyllaclusters.scylla.scylladb.com "basic" not found

What is use case behind this feature:

Additional Information: We need to support the scale subresource.

[tnozicka]

I suppose would scale the members in every rack.

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[tnozicka]

@zimnx this might be a good one to look at for ScyllaDBDatacenter

[tnozicka]

We have decided to postpone it in favour of a dedicated proposal, but for the future some context on the complexities is in https://github.com/scylladb/scylla-operator/pull/1994#discussion_r1672035663