Add support for CEL validation to our CRDs

[scholzj]

Type of change

• Enhancement / new feature

Description

This PR adds support for using CEL validations in our CRDs. It uses an annotation to add the CEL validation rules on a type or on a getter.

The CEL validation rules can be used to improve the validation of our CRDs beyond what the OpanAPI allows. Right now, this PR does not add the rules to any actual API classes. But it is expected to be used for example here: #11051 (review) to make the valueFrom field required when using jmxPrometheusExporter metrics.

In general, the CEL validation rules should not be used for any existing fields to make the validation more strict than it was before, as that might cause backward compatibility issues. It should be used only for new APIs or when we remove some previous restrictions (such as in #11051 where the valueFrom field is made conditionally optional instead of required).

The Pr adds support for all the options of the CEL validation rules. However, fieldPath and reason do not seem to be supported until Kube 1.28. So it should not be used yet in Strimzi

This PR should close #9417.

Checklist

• Write tests
• Make sure all tests pass
• Try your changes from Pod inside your Kubernetes and OpenShift cluster, not just locally
• Reference relevant issue(s) and close them after merging

[ppatierno]

LGTM.

[katheris]

LGTM and this looks like a great feature to be able to use in future