App/Gui: New restoreError Document status and Gui pop-up

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If the restore of Document.xml results in invalid Document.xml (because unhandled exceptions occurred), the
document status Document::restoreError is set. The GUI or Mod/Web if a link was clicked, show a pop-up indicating
this situation.

This commit also shows an appropriate pop-up for the partialRestore when opening from the menu, that before only
appeared when opening by clicking a link.

src/App/Document.cpp

@@ -2745,6 +2745,7 @@ void Document::restore (const char *filename,
     }
     catch (const Base::Exception& e) {
         Base::Console().Error("Invalid Document.xml: %s\n", e.what());
+        setStatus(Document::RestoreError, true);
     }
 
     d->partialLoadObjects.clear();