unable to query config contexts

[mattsawyer77]

I was wondering if it might be possible to expose the config utils module. My use case requires the ability to get a list of named contexts from the config. But if I'm reading the code right this is impossible.

[clux]

I think the Config struct is exposed. You could serialize the kube config file into that struct using serde_yaml. Although I think it's actually pretty reasonable to let users do this. We should just expose Config::load_config.

[clux]

Made a PR for this in #125 - might tweak it a bit. But we ought to have something like this.