add plural to Resource and GroupVersionKind

[clux]

replaces #468.
closes #467

This changes kube-derive to no longer implement k8s_openapi traits.
We now instead implement kube::Resource instead so we can control the plural.

Because the trait now picks up on an override when it is generating the path_url, it is now correct in the Api urls.

[clux]

One slightly awkward thing about this is that it sets up a cycle:

• kube: depends on kube-derive so it can re-export it
• kube-derive: depends on kube for kube::Resource

Not sure this is problematic or not. We avoided it before because the trait came from k8s_openapi, but now we would have to have a kube-traits or something. I don't think this causes any problems though?

EDIT: It does seem to be a problem. Will have to look into it later in the week as unless someone has suggestions.
EDIT2: Fixed it. Needed only to have dev-dependency from kube-derive back into kube plus make sure symbols existed in one stray test.

[clux]

Released in 0.52.0.