## Context

Adds a tool to utilize the UI we already expose to ACP agents. Behind a
feature flag for now.

## How to Review

Mostly a tool to hook up to all of the plan plumbing we already have in
acp thread.

## Self-Review Checklist

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A