Make the thematic Icons sections in the Collection collapsible

There are pretty many different themes and some of them are also pretty large. I really like the whole arrangement but the Icons in general are very plenty and that will of course become even more in the future. There are some thematics like esports or soccer cup icons that I don't really need to see and there it'd be cool if I could collapse them so it is more clearly to scroll through the icons I actually want to see. Just a little implementation that doesn't hurt anyone =)