[wip] native Kubernetes client

[timothyb89]

This adds a native Kubernetes client to replace the kubectl proxy subprocess. That is, a kubeconfig parser with some integration with reqwest to configure proxies and auth, or the rust equivalent of tiny-kubernetes. It only strictly needs serde_yaml, reqwest, and base64.

Ideally this should end up being much smaller than a 'proper' client and can easily support the few functions we actually care about (auth, proxies, streamed responses, websockets, exotic kubeconfig formats, ...).

This at least properly parses all the kubeconfigs I have handy, including minikube, microk8s, eks, kubeadm, and a few others.

Closes #28