WebUI: fix adding torrent when using virtual tables

When using virtual tables we can't rely on fetching the values from the DOM. We should always fetch values directly from the file tree.

PR #23263.
Closes #23241.

src/webui/www/private/scripts/dynamicTable.js

@@ -2478,6 +2478,10 @@ window.qBittorrent.DynamicTable ??= (() => {
                 this.#addNodeToTable(child, depth + 1, node);
         }
 
+        getFileTreeArray() {
+            return this.fileTree.toArray();
+        }
+
         getRoot() {
             return this.fileTree.getRoot();
         }