+ Added cart system (Disabled by default)

The cart system, if enabled allows players to add multiple non biddable items to their cart and checkout all at once rather than going through one by one.

/ah cart can be used to view the cart directly (auctionhouse.cmd.cart) or if you toggle the new setting "replace guide with cart button" it'll place the cart icon by default in the bottom right slot of the gui.

https://prnt.sc/6-OHMYRLmWFQ
https://gyazo.com/13c4340bee66301cac6fcccd2941df5c