rpc: Remove `llm` module in favor of `zed_llm_client` (#28900)

This PR removes the `llm` module of the `rpc` crate in favor of using
the types from the `zed_llm_client`.

Release Notes:

- N/A
fcb1efdf21Marshall Bowers committed on 4/16/2025, 8:22:44 PM· committed by GitHubparent54b46fd
9 files changedLine totals unavailable