Since #12241 we have notifications for this when the user navigates away from the viewer, but we do not yet warn when switching documents, which means that if you call e.g. `PDFViewerApplication.open` with a new document (or directly call `BaseViewer.setDocument` when using the viewer components standalone) there won't be any warning about losing form data. This should be addressed.
const { eventBus, _boundEvents } = this;
    _boundEvents.windowResize = () => {
      eventBus.dispatch("resize", { source: window });
    };
    _boundEvents.windowHashChange = () => {
      eventBus.dispatch("hashchange", {
        source: window,
        hash: document.location.hash.substring(1),
      });
    };