ui: More component previews, UI component cleanup (#25302)

- Don't require ui component docs (this isn't really working)
- Add more component previews
- Update component preview style & navigation

Release Notes:

- N/A

crates/collab_ui/src/collab_panel.rs

@@ -2458,8 +2458,8 @@ impl CollabPanel {
                 Avatar::new(contact.user.avatar_uri.clone())
                     .indicator::<AvatarAvailabilityIndicator>(if online {
                         Some(AvatarAvailabilityIndicator::new(match busy {
-                            true => ui::Availability::Busy,
-                            false => ui::Availability::Free,
+                            true => ui::CollaboratorAvailability::Busy,
+                            false => ui::CollaboratorAvailability::Free,
                         }))
                     } else {
                         None