editor: Shrink DisplayMapSnapshot from 824 to 256 bytes (#39568)

We have unnecessary clones for the fields here as most of the snapshots
contain the others hierarchically.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/collab_ui/src/channel_view.rs

@@ -248,7 +248,7 @@ impl ChannelView {
             .editor
             .update(cx, |editor, cx| editor.snapshot(window, cx));
 
-        if let Some(outline) = snapshot.buffer_snapshot.outline(None)
+        if let Some(outline) = snapshot.buffer_snapshot().outline(None)
             && let Some(item) = outline
                 .items
                 .iter()
@@ -305,7 +305,7 @@ impl ChannelView {
 
         let mut closest_heading = None;
 
-        if let Some(outline) = snapshot.buffer_snapshot.outline(None) {
+        if let Some(outline) = snapshot.buffer_snapshot().outline(None) {
             for item in outline.items {
                 if item.range.start.to_display_point(&snapshot) > position {
                     break;