Add the option to bind cosmetic items to decks

It would be nice if players could assign cosmetic items to decks, for example: my default avatar is the tree sprite, but if I play my blue deck my avatar would be Aurora, since I have assigned Aurora as the avatar for that deck. Or my default card back is the unique steam card back, but when I play my yellow rush deck I would use the dragon card back instead, because I have chosen the dragon card back for that deck. This is definitively not crucial for my enjoyment of the game, but it would be neat function.