Remove additional wrapping elements in the chat panel (#14013)

This PR removes some wrapping elements that were used inside of the chat
panel.

To facilitate this, the `Label` component now has a `weight` method to
change the font weight.

Release Notes:

- N/A

crates/ui/src/components/label/highlighted_label.rs

@@ -1,6 +1,6 @@
 use std::ops::Range;
 
-use gpui::{HighlightStyle, StyledText};
+use gpui::{FontWeight, HighlightStyle, StyledText};
 
 use crate::{prelude::*, LabelCommon, LabelLike, LabelSize, LineHeightStyle};
 
@@ -29,6 +29,11 @@ impl LabelCommon for HighlightedLabel {
         self
     }
 
+    fn weight(mut self, weight: FontWeight) -> Self {
+        self.base = self.base.weight(weight);
+        self
+    }
+
     fn line_height_style(mut self, line_height_style: LineHeightStyle) -> Self {
         self.base = self.base.line_height_style(line_height_style);
         self