"recipe_result": New Loot Table Entry Type

Loot table entries can currently add items directly with "type": "item" or from other loot tables with "type": "loot_table". I think now that we can specify custom items using recipes (with components on the result), we should be able to directly reference those custom items within a loot table. An acceptable loot table entry of this form might look something like this:

{
    "type": "recipe_result",
    "recipe": "recipe_name_here",
    "weight": 1,
    "conditions": [...],
    "functions": [...]
}

That way, in datapacks which create custom items, we'd be able to create an item definition in one place (the recipe) and then reference it elsewhere. Currently, if you want to make a custom item craftable AND have it appear in loot tables, you have to define it twice - once for the recipe and once for the loot table - which feels redundant, and also could lead to some compatibility issues if the datapack isn't updated perfectly.