Infinite Page Scroll Restoration

[korgon]

Currently when using infinite scroll the restorePosition is helpful in navigating back to the product that was last viewed. However, if no product was clicked on, there will be nowhere to scroll, so landing on a URL with ?page=8 will start at the top of the page. We could improve this by adding a setting for infinite configuration so that if there is no element in the scrollMap, we could automatically add the first product on the 8th page - this would restore the position to that product on page load as long as no other product was set to be scrolled to.