Draft: Spike proxying raw bytes to agent(w/k)

Issue:

Spike: Compare and contrast between using gRPC ... (gitlab-org/gitlab#547416 - closed)

What does this MR do?

This MR is a spike that sets up KAS to proxy raw incoming bytes over to an agent instance. The agent instance then proxies the stream onto a local TCP connection and forwards the replied stream back to KAS, which returns it to the original client.

This is done in an attempt at a POC to proxy an SSH connection from a client to a workspace. As the in-progress agentW setup is not ready/requires additional configuration, This spike MR takes some liberties (and unfortunately, naming inconsistencies) to use the existing agentK setup for the spike.

This MR is intended to be paired with the client code in this repo to test.