language_model: Remove dependency on ui (#27448)

This PR removes the dependency on the `ui` crate from the
`language_model` crate.

We were only depending on it to import `IconName`—which now lives in
`icons`—and some re-exported GPUI items.

Release Notes:

- N/A

crates/language_model/src/language_model.rs

@@ -13,6 +13,7 @@ use client::Client;
 use futures::FutureExt;
 use futures::{future::BoxFuture, stream::BoxStream, StreamExt, TryStreamExt as _};
 use gpui::{AnyElement, AnyView, App, AsyncApp, SharedString, Task, Window};
+use icons::IconName;
 use proto::Plan;
 use schemars::JsonSchema;
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
@@ -20,7 +21,6 @@ use std::fmt;
 use std::ops::{Add, Sub};
 use std::{future::Future, sync::Arc};
 use thiserror::Error;
-use ui::IconName;
 use util::serde::is_default;
 
 pub use crate::model::*;