ui2: Unsuppress and fix warnings (#3423)

This PR unsupresses the warnings in `ui2` and summarily fixes them.

Release Notes:

- N/A

crates/ui2/src/components/label.rs

@@ -1,6 +1,6 @@
 use crate::prelude::*;
 use crate::styled_ext::StyledExt;
-use gpui::{relative, Div, Hsla, IntoElement, StyledText, TextRun, WindowContext};
+use gpui::{relative, Div, IntoElement, StyledText, TextRun, WindowContext};
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Default)]
 pub enum LabelSize {
@@ -182,9 +182,3 @@ impl HighlightedLabel {
         self
     }
 }
-
-/// A run of text that receives the same style.
-struct Run {
-    pub text: String,
-    pub color: Hsla,
-}