Websocket implementation for connect_core_v1_get_namespaced_pod_exec

[benwbooth]

Currently there doesn't appear to be a websocket implementation for connect_core_v1_get_namespaced_pod_exec. It would be great to have one. The python k8s client has an implementation here. The ws crate could be used for the implementation. Thanks!

[ynqa]

@benwbooth Thanks, we will tackle this issue for gold-requirements later.

Support exec, attach, port-forward calls (these are not normally supported out of the box from swagger-codegen)