Use protobuf content type instead of JSON for k8s API calls

[bpoland]

The Kubernetes docs say this about content type for API requests:

Although JSON is the default, clients may request the more efficient binary Protobuf representation for better performance at scale.

Based on a quick search here I don't think agent-stack-k8s is doing that (and it is not enabled by default in the k8s go client) -- would you consider either defaulting to protobuf or allowing it to be switched on with some configuration? It appears the implementation would be relatively simple e.g. https://github.com/kubernetes-sigs/aws-ebs-csi-driver/pull/2138/files

Thanks!

[dabarrell]

Hey @bpoland! Looks like it could be a possible improvement! It's not going to be something on our immediate radar, but we'd be happy to review a PR if you put one together.