Parameterize avatar_margin and assign it a default of 8

crates/theme/src/theme.rs

@@ -53,6 +53,7 @@ pub struct Titlebar {
     pub height: f32,
     pub title: TextStyle,
     pub avatar_width: f32,
+    pub avatar_margin: f32,
     pub avatar_ribbon: AvatarRibbon,
     pub offline_icon: OfflineIcon,
     pub share_icon: Interactive<ShareIcon>,

crates/workspace/src/workspace.rs

@@ -1629,7 +1629,7 @@ impl Workspace {
             .constrained()
             .with_width(theme.workspace.titlebar.avatar_width)
             .contained()
-            .with_margin_left(2.)
+            .with_margin_left(theme.workspace.titlebar.avatar_margin)
             .boxed();
 
         if let Some(peer_id) = peer_id {