Dial in the channel creating/renaming UI

* Ensure channel list is in a consistent state with no flicker while the
  channel creation / rename request is outstanding.
* Maintain selection properly when renaming and creating channels.
* Style the channel name editor more consistently with the non-editable
  channel names.

Co-authored-by: Mikayla <mikayla@zed.dev>

styles/src/style_tree/collab_panel.ts

@@ -358,7 +358,7 @@ export default function contacts_panel(): any {
         face_overlap: 8,
         channel_editor: {
             padding: {
-                left: 8,
+                left: name_margin,
             }
         }
     }