This change:
1. Catches attempts to use missing tools. If this happens, we now send
Agent a message listing available tools, after which Agent can
gracefully recover. Prior behavior: thread would stop in a broken state.
Example of a hallucinated call and a message we send back:

2. Adds evals for hallucinated tool use and imagined edits
3. Adds ability to configure a profile name in evals.
Release Notes:
- N/A
I also introduced a new eval to prove the encouragement actually makes a
difference.
Release Notes:
- Improved agent behavior when streaming edits, encouraging it to
editing files as opposed to creating them from scratch