Fetch ClientConfig.

Fetch rest.Config for environment in which this is invoked, override the API Server URL and current context if specified.

NewApiPortForwarder returns an implementation of a PortForwarder that does not rely on the Kubernetes CLI but instead queries the Kubernetes API directly This implementation is preferred, but we have seen it fail occassionally with the following error: portforward.go:394] error copying from local connection to remote stream: EOF.

NewCliPortForwarder returns an implementation of a PortForwarder that relies on the Kubernetes CLI to perform port-forwarding This implementation is NOT thread-safe.

NewPortForwarder returns an implementation of a PortForwarder.

WithResourceSelector takes a kubectl-style selector like `deployment/<name>` or `pod/<name>` and tries to construct the correct Option for it.

PortForwarder manages the forwarding of a single port.