assistant_context_editor: Register `ContextEditor` actions that were lost (#30428)
Marshall Bowers
created
This PR restores the `ContextEditor` actions that were lost in
https://github.com/zed-industries/zed/pull/30168.
Closes https://github.com/zed-industries/zed/issues/30356.
Release Notes:
- agent: Added back some missing actions, including `assistant: quote
selection`.