Furniture and terrain can have custom field sprites

[bombasticSlacks]

Summary

Features "Furniture and terrain can have custom field sprites"

Purpose of change

Someone on the discord made a fantastic fire barrel sprite that was animated. It didn't work in game instead showing the basic fire sprite. So I've made it so fields can have specific sprites for furniture / terrain similar to #52632

Describe the solution

Made the layering.json more robust so it can handle an array of field variants as well per context

Renamed some of the json keys to support this more clearly

Describe alternatives you've considered

Testing

fire barrel working in game.

tested some other layer stuff (like toilet water) to make sure they didn't break

Additional context