With the recent PR 7172, which made the viewer modular, there's now a couple of modules that are no longer easily accessible (e.g. through the console).
This can make testing/debugging more difficult, and means that e.g. https://github.com/mozilla/pdf.js/wiki/Debugging-PDF.js#enabling no longer works in the generic viewer.
For now, as a simple solution, this patch just exposes those non-classes on `PDFViewerApplication` to ensure that they are available, and to avoid polluting the `window` scope.
This is a regression from PR 7097.
(Also, out of scope for this PR, but I think that a `setTimeout` value of `1000 ms` is too large. Switching from scrolling to zooming can fell sluggish, and give the impression that nothing happens.)
