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;
    eventBus._off("resize", webViewerResize);
    eventBus._off("hashchange", webViewerHashchange);
    eventBus._off("beforeprint", _boundEvents.beforePrint);
    eventBus._off("afterprint", _boundEvents.afterPrint);
    eventBus._off("pagerendered", webViewerPageRendered);
    eventBus._off("updateviewarea", webViewerUpdateViewarea);
    eventBus._off("pagechanging", webViewerPageChanging);
    eventBus._off("scalechanging", webViewerScaleChanging);
    eventBus._off("rotationchanging", webViewerRotationChanging);
    eventBus._off("sidebarviewchanged", webViewerSidebarViewChanged);
    eventBus._off("pagemode", webViewerPageMode);
    eventBus._off("namedaction", webViewerNamedAction);
    eventBus._off("presentationmodechanged", webViewerPresentationModeChanged);
    eventBus._off("presentationmode", webViewerPresentationMode);
    eventBus._off("print", webViewerPrint);
    eventBus._off("download", webViewerDownload);
    eventBus._off("save", webViewerSave);
    eventBus._off("firstpage", webViewerFirstPage);
    eventBus._off("lastpage", webViewerLastPage);
    eventBus._off("nextpage", webViewerNextPage);
    eventBus._off("previouspage", webViewerPreviousPage);