tsk-62: Use QueuedSong and QueuedCoverArt to replace references to path of Song and CoverArt (#64)

Closes #62

Reviewed-on: #64
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

src/queued_item.rs

@@ -0,0 +1,13 @@
+#[derive(Clone, Debug, Default)]
+pub struct QueuedSong {
+    pub id: uuid::Uuid,
+    pub song: icarus_models::song::Song,
+    pub path: String,
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct QueuedCoverArt {
+    pub id: uuid::Uuid,
+    pub coverart: icarus_models::coverart::CoverArt,
+    pub path: String,
+}