Add support for `v1.APIVersions` in KubernetesClient

[rohanKanojia]

Is your task related to a problem? Please describe

I bumped into this issue while writing tests for eclipse-jkube/jkube#2663 where I use KubernetesMockServer via Helm CLI.

Kubernetes APIServer provides an endpoint to allow clients to discover the API at /api which is the root path of the legacy v1 API.

I'm not able to see any support in KubernetesClient for achieving this. APIVersions object is also absent from Kubernetes Model

Describe the solution you'd like

• APIVersions resource is added to Kubenetes Model
• Support for /api endpoint is added to KubernetesClient DSL

Describe alternatives you've considered

I'm using raw JSON string at the moment as a workaround that's a bit ugly.

Additional context

No response

[manusa]

We do have logic in place for /apis (APIGroupList, APIGroup).

And also for /api/v1 -or any other version- (APIResourceList, APIResource).

See getApiGroups and getApiResources.

Can you please elaborate on the use-case of this or on why it's specifically needed.

[rohanKanojia]

/api/v1 returns a APIResourceList just like /apis/{group}/{version}

/api endpoint is different as it allows clients to discover the API server. It's used by kubectl and helm CLI before making any request.

If we want to provide support for /api endpoint in Kubernetes Mock Server #6062 . We need to at least provide model support for this resource.