Use LiveKit's Rust SDK on Linux while continue using Swift SDK on Mac (#21550)

Similar to #20826 but keeps the Swift implementation. There were quite a
few changes in the `call` crate, and so that code now has two variants.

Closes #13714

Release Notes:

- Added preliminary Linux support for voice chat and viewing
screenshares.

---------

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
Co-authored-by: Kirill Bulatov <kirill@zed.dev>
Co-authored-by: Mikayla <mikayla@zed.dev>

crates/collab_ui/src/collab_panel.rs

@@ -474,11 +474,10 @@ impl CollabPanel {
                             project_id: project.id,
                             worktree_root_names: project.worktree_root_names.clone(),
                             host_user_id: participant.user.id,
-                            is_last: projects.peek().is_none()
-                                && participant.video_tracks.is_empty(),
+                            is_last: projects.peek().is_none() && !participant.has_video_tracks(),
                         });
                     }
-                    if !participant.video_tracks.is_empty() {
+                    if participant.has_video_tracks() {
                         self.entries.push(ListEntry::ParticipantScreen {
                             peer_id: Some(participant.peer_id),
                             is_last: true,