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/model/cloud_model.rs

@@ -6,13 +6,13 @@ use client::Client;
 use gpui::{
     App, AppContext as _, AsyncApp, Context, Entity, EventEmitter, Global, ReadGlobal as _,
 };
+use icons::IconName;
 use proto::{Plan, TypedEnvelope};
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use smol::lock::{RwLock, RwLockUpgradableReadGuard, RwLockWriteGuard};
 use strum::EnumIter;
 use thiserror::Error;
-use ui::IconName;
 
 use crate::LanguageModelAvailability;