✨ Add ClusterClass support for EKS clusters

[alexander-demicev]

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What type of PR is this? /kind feature

What this PR does / why we need it:

This PR adds ClusterClass support for EKS.

• It doesn't support managed machine pools for now, I will add them in a follow up
• I'm unsure which fields in AWSManagedControlPlane can be reused in AWSManagedControlPlaneTemplate so please correct me if I'm wrong.
• Moving some fields to a nested structure in AWSManagedControlPlane broke conversions and they have to be done manually.

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 https://github.com/kubernetes-sigs/cluster-api-provider-aws/issues/3166

Special notes for your reviewer:

Checklist:

• [x] squashed commits
• [ ] includes documentation
• [x] includes emoji in title
• [x] adds unit tests
• [ ] adds or updates e2e tests

Release note:

Add ClusterClass support for EKS clusters