Scale diagnostic headers icons with editor font and right align w/ line numbers

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/editor/src/display_map/block_map.rs

@@ -69,7 +69,9 @@ where
 pub struct BlockContext<'a> {
     pub cx: &'a AppContext,
     pub anchor_x: f32,
-    pub line_number_x: f32,
+    pub gutter_width: f32,
+    pub gutter_padding: f32,
+    pub em_width: f32,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -947,7 +949,9 @@ mod tests {
                         .render(&BlockContext {
                             cx,
                             anchor_x: 0.,
-                            line_number_x: 0.,
+                            gutter_padding: 0.,
+                            gutter_width: 0.,
+                            em_width: 0.,
                         })
                         .name()
                         .unwrap()