Add field support.

[IoIxD]

Spigot devs really love their weird "it's not an enum, it's class with a bunch of static fields" classes, huh?

Add support for static fields (and maybe regular fields? idk)

[IoIxD]

Actually this is low priority because some of these classes have methods that let you work around it anyways. See: Enchantment which has a getByName function

[IoIxD]

I forgot that this was the reason I wanted this, I actually ended up doing this anyways but only for enums.

So it's even lower priority because idk what else in the library uses this.