[Old UI] Enable Upsell Popup to add more than one item at once

As of October 2019, if you're on Version 3 of Cross Sell, you can now let customers choose more than one suggestion after it's been added to the cart.

To enable this feature, go to Settings -> Quickview & Upsell Pop-up -> Upsell Pop-up section -> Check the box that says "Continue to show the Upsell Pop-up when selecting Add to cart button"