Add Open in New Window context menu action to sidebar items

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -462,6 +462,21 @@ extension MainSidebarViewController: UICollectionViewDelegate {
             return true
         }
     }
+    
+    func collectionView(_ collectionView: UICollectionView, contextMenuConfigurationForItemAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
+        guard #available(iOS 15.0, *),
+              let item = dataSource.itemIdentifier(for: indexPath),
+              let activity = userActivityForItem(item) else {
+            return nil
+        }
+        return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { (_) in
+            return UIMenu(children: [
+                UIWindowScene.ActivationAction({ action in
+                    return UIWindowScene.ActivationConfiguration(userActivity: activity)
+                }),
+            ])
+        }
+    }
 }
 
 extension MainSidebarViewController: UICollectionViewDragDelegate {