Final Config interface for v3.0.0

[Adirio]

The Config interface has 2 methods that seem a bit out of place.
IsCRDVersionCompatible and IsWebhookVersionCompatible encode inside a project configuration version the possibility of having only one or multiple different CRD/webhook versions. While this check is needed as we are not supporting multiple CRD/webhook versions, the project configuration itself is not th elimiting factor. A better API design would be replacing these two methods by ListCRDVersions() []string and ListWebhookVersions() []string letting the plugins be the ones that check if they are valid. This would allow a future plugin go/v4 accept multiple CRD versions in a single project but still use project version 3.

/remove-kind feature