kfctl: support deploy with basic auth

[kunmingg]

User should be able to deploy cluster with go binary while provide username/password to later access their kubeflow service

[kunmingg]

/cuj build-train-deploy

[jlewi]

/label cuj/build-train-deploy

[jlewi]

@kunmingg @gabrielwen who is planning on working on this?

[gabrielwen]

@kunmingg added both of configs for me and I'm gonna use them on go kfctl.

[kunmingg]

Config entry used by ktctl:
#2482