General purpose way to add Agents

[rsmith49]

A way to support any CodeAgent that points to an arbitrary base_url. The challenge is in being able to field the LLM requests from the agent and respond to them from the agent during training.

The current proposal is to:

1. Install and run the agent in the container after pointing it to a particular URL
2. Run a server that is able to act as the agent and return LLM requests (probably via some pub/sub mechanism)