[Feature] Brewable burritos and snack cakes

[Noah Buttes]

What this patch does:

• Enables individuals to brew discount dan burritos and snack cakes using the barman's portable still. 
  
• Establishes an easily extensible framework for expansion to other future dan items
  
• Not create an infinite burrito loop like the first version of the patch did
  
• Be incredibly gross
  

Known compatibility issues:
None except for weak stomachs.

How to expand to other dan products:

Include something akin to the following underneath the product:

Code:

brewable = 1
brew_result = list("sewage", "ethanol")

Then just add the product's path to this:

Code:

if (istype(W,/obj/item/reagent_containers/food/snacks/snack_cake) || istype(W,/obj/item/reagent_containers/food/snacks/burrito))

Compare: https://github.com/goonstation/goonstati...e-burritos

Patch: https://github.com/goonstation/goonstati...itos.patch