Revert "CuraApplication/UM.MeshBuilder: Removing _reloadMeshFinished"

This reverts commit 269b52487ed28e42daf7e2716117c4d3d27bc2fa. It was crashing Cura when pressing F5.
The completion of this job should not be moved to Uranium because the job exists only in Cura.

Contributes to issue CURA-4912.

cura/CuraApplication.py

@@ -1307,7 +1307,7 @@ class CuraApplication(QtApplication):
             if file_name:
                 job = ReadMeshJob(file_name)
                 job._node = node
-                job.finished.connect(node._reloadJobFinished)
+                job.finished.connect(self._reloadMeshFinished)
                 job.start()
             else:
                 Logger.log("w", "Unable to reload data because we don't have a filename.")
@@ -1436,6 +1436,14 @@ class CuraApplication(QtApplication):
     fileLoaded = pyqtSignal(str)
     fileCompleted = pyqtSignal(str)
 
+    def _reloadMeshFinished(self, job):
+        # TODO; This needs to be fixed properly. We now make the assumption that we only load a single mesh!
+        mesh_data = job.getResult()[0].getMeshData()
+        if mesh_data:
+            job._node.setMeshData(mesh_data)
+        else:
+            Logger.log("w", "Could not find a mesh in reloaded node.")
+
     def _openFile(self, filename):
         self.readLocalFile(QUrl.fromLocalFile(filename))