Makes immersive item slots centered so it looks nicer. It'll be a config option that's off by default and won't be synced from the server. Only planned for furnace and possibly brewing stand, as others either align with the block texture (crafting table and jukebox) or align in an already centered sort of way (chest).

May need to do this for the anvil and/or enchanting table once those are added, though.

Instead, let's break down auto center into alternative modes for immersives:
Alt Furnace: Item centering as described above
Alt Brewing: Item centering as described above