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/request.rs

@@ -5,11 +5,11 @@ use crate::role::Role;
 use crate::{LanguageModelToolUse, LanguageModelToolUseId};
 use base64::write::EncoderWriter;
 use gpui::{
-    point, size, App, AppContext as _, DevicePixels, Image, ObjectFit, RenderImage, Size, Task,
+    point, px, size, App, AppContext as _, DevicePixels, Image, ObjectFit, RenderImage,
+    SharedString, Size, Task,
 };
 use image::{codecs::png::PngEncoder, imageops::resize, DynamicImage, ImageDecoder};
 use serde::{Deserialize, Serialize};
-use ui::{px, SharedString};
 use util::ResultExt;
 
 #[derive(Clone, PartialEq, Eq, Serialize, Deserialize, Hash)]