[Acroform] Use the full path to find the node in the XFA datasets where to store the value

I noticed several 'Path not found' errors because of a field called #subform[2].
From the XFA specs, the hash is used for a class of elements in the template tree.
When we're looking for a node in the datasets tree, it doesn't make sense to search
for a class. Hence the path element starting with a hash are just skipped.

src/core/worker.js

@@ -831,6 +831,13 @@ class WorkerMessageHandler {
       setupDoc(docParams);
       docParams = null; // we don't need docParams anymore -- saving memory.
     });
+
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
+      handler.on("GetXFADatasets", function (data) {
+        return pdfManager.ensureDoc("xfaDatasets");
+      });
+    }
+
     return workerHandlerName;
   }