[5092] CraftingFactoriesRegisterEvent & Allow for actual Resource Locations

[Ecdcaeb]

Fix https://github.com/MinecraftForge/MinecraftForge/issues/5092 and provide a new event which enable register/unregister factories;

Why I could not use _factories.json to define it? But a event?

Of course you can use json, but using events is more dynamic, without reflection, and suitable for mods with missing resources.

Why dynamic registration is needed

There is currently no way to selectively register Json, and the conditional syntax designed by Forge for Json cannot be used on it. When I create a Factory for a optional dependency, however, I have to mark it as a required-dependency.

When will resources be missing?

Coremod，or the broken env.