Adjusting "Back to top" to consider the `wheel` event

[pradyunsg]

Discussed in #421

^{Originally posted by jdknight April 16, 2022}
The existing scroll handler logic ties everything to the scroll event. I'm wondering if it would be possible to adjust the "Back to top" implementation to also consider the wheel event (when applicable), to help avoid rendering the back-to-top overlay when a page is scrolled via navigation events (back/forward; and menu clicks on the sidebar).