New Procedure for item automation

Two new procedures for automating item transport:

both using code from IItemHandler in package net.neoforged.neoforge.items;

1. Get Number of Slots: 

Returns number of slots in a gui, using: int getSlots();

2. Is Slot (SlotID) an Input slot:

Returns a boolean if a stack amount of items can be put into a slot, using: boolean isItemValid(int slot, ItemStack stack);