Describe the solution you'd like:
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Currently, the KCP references an IONOSCloudMachine which defines a spec. availabilityZone.
The availability zone can be set to AUTO, which will let IONOS cloud decide.
But might the decision be not convenient for a HA setup

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

We need a way of distributing control-plane nodes to different zones.

Proposal

Add a new field spec. availabilityZones which is mutually exclusive with spec. availabilityZone.
Always spec. availabilityZone take precedence.

whenever spec. availabilityZones is set and machine type is CP, CAPIC needs to get the KCP machines and round robin the zones for each machine.