language_models: Pass up `mode` for completion requests through Zed (#29294)

This PR makes it so we pass up the `mode` for completion requests
through the Zed provider.

Release Notes:

- N/A
92e810bfecMarshall Bowers committed on 4/23/2025, 6:02:03 PM· committed by GitHubparent724c935
3 files changedLine totals unavailable