feat(opengraph): change mature hub game preview icon to actual game icon, add hub icon

[drisc]

This PR changes the mature game icon shown via the gate to the sets actual icon. Several people have pointed out that we don't allow NSFW imagery in set icons anyway so it makes little sense to obscure it. When a user clicks through the link they will be presented with the mature gate if they are not logged in or do not have the mature webpref set.

This PR also adds Hub images to link previews as currently they just show the default RA logo.