Add user-visible output for remote operations (#25849)

This PR adds toasts for reporting success and errors from remote git
operations. This PR also adds a focus handle to notifications, in
anticipation of making them keyboard accessible.

Release Notes:

- N/A

---------

Co-authored-by: julia <julia@zed.dev>

crates/language/src/buffer.rs

@@ -590,7 +590,7 @@ impl HighlightedText {
 
     pub fn to_styled_text(&self, default_style: &TextStyle) -> StyledText {
         gpui::StyledText::new(self.text.clone())
-            .with_highlights(default_style, self.highlights.iter().cloned())
+            .with_default_highlights(default_style, self.highlights.iter().cloned())
     }
 
     /// Returns the first line without leading whitespace unless highlighted