feat: queue videos in running player

src/youtube.rs

@@ -929,6 +929,7 @@ impl PlayerLaunch {
         videos: &[Video],
         player: &OsStr,
         state: &mut crate::video_state::State,
+        enqueue: bool,
     ) -> io::Result<Self> {
         if videos.is_empty() {
             return Err(io::Error::new(
@@ -937,8 +938,14 @@ impl PlayerLaunch {
             ));
         }
         let mut command = isolated_command(player);
-        command.arg("--new-instance");
-        if let [video] = videos {
+        command.arg(if enqueue {
+            "--enqueue"
+        } else {
+            "--new-instance"
+        });
+        if let [video] = videos
+            && !enqueue
+        {
             let url = video_url(&video.id)?;
             let report = state.progress_file(video)?;
             crate::video_state::register_identity(&report, &video.id)?;