Adding datapack capabilities for secondary smelting outputs

If you put a bucket in the fuel slot of a furnace drying a wet sponge, the bucket fills up with water when the recipe finishes processing. Adding this secondary output functionality to datapacks would allow creators to add a large variety of diversity to new smelting, blasting, and smoking recipes.

Example of what the sponge.json recipe could look like, with the new fields bolded:

{
  "type": "minecraft:smelting",
  "category": "blocks",
  "cookingtime": 200,
  "experience": 0.15,
  "ingredient": {
    "item": "minecraft:wet_sponge"
  },
  "secondary_result": {
     "ingredient": "minecraft:bucket",
     "result": "minecraft:water_bucket"
  },
  "result": {
    "id": "minecraft:sponge"
  }
}

These fields would be optional to reduce the total file size of smelting, blasting, and smoking recipe.

Considered the add-on topic due to being closely related to datapacks.