Make outline modal work in channel notes (#39481)

This fixes an issue where the outline modal would not work in editors
that had no explicit workspace attached to them.

Release Notes:

- Enabled the outline modal to work in channel notes.

crates/outline/src/outline.rs

@@ -20,7 +20,7 @@ use settings::Settings;
 use theme::{ActiveTheme, ThemeSettings};
 use ui::{ListItem, ListItemSpacing, prelude::*};
 use util::ResultExt;
-use workspace::{DismissDecision, ModalView};
+use workspace::{DismissDecision, ModalView, Workspace};
 
 pub fn init(cx: &mut App) {
     cx.observe_new(OutlineView::register).detach();
@@ -48,7 +48,8 @@ pub fn toggle(
         .snapshot(cx)
         .outline(Some(cx.theme().syntax()));
 
-    if let Some((workspace, outline)) = editor.read(cx).workspace().zip(outline) {
+    let workspace = window.root::<Workspace>().flatten();
+    if let Some((workspace, outline)) = workspace.zip(outline) {
         workspace.update(cx, |workspace, cx| {
             workspace.toggle_modal(window, cx, |window, cx| {
                 OutlineView::new(outline, editor, window, cx)