get Parent
The parent of this key (This is usually used as getClassById namespace)
For example: If the key is "net.minecraft.gameplay.gamemode" this would return "net.minecraft.gameplay" If the key is "minecraft" this would return ROOT_KEY
The parent of the key X levels above
For example: If the key is "net.minecraft.gameplay.gamemode" getParent(2) would return "net.minecraft"