Don't warn when navigating away from a modified form, if printing has occurred (issue 12262)

This solution is obviously *not* perfect, since printing being cancelled will thus remove the warning as well. However, a similar problem already exists for saving, since the user may cancel that one as well.

All-in-all, since way cannot really detect with absolute certainty that either saving or printing actually finished, this seems good enough for now.

web/app.js

@@ -1687,6 +1687,10 @@ const PDFViewerApplication = {
     if (this.printService) {
       this.printService.destroy();
       this.printService = null;
+
+      if (this.pdfDocument) {
+        this.pdfDocument.annotationStorage.resetModified();
+      }
     }
     this.forceRendering();
   },