Lots of fixes for track management

tests/integration.rs

@@ -86,6 +86,10 @@ impl SearchProvider for MockSearch {
             ],
         })
     }
+
+    async fn get_release_groups(&self, _artist_id: &str) -> SearchResult<Vec<shanty_search::ReleaseGroupResult>> {
+        Ok(vec![])
+    }
 }
 
 #[tokio::test]