Added item drop functionality.

-Now when player has full inventory, they will be prompted to discard an item
after defeating an enemy either during their turn or enemy turn.
-If discarding an item already in their inventory, the dropped item will be placed into that respective slot; otherwise they can just discard the dropped item.
-Player's turn ends after discarding any item in this situation.
-New button 'dropped_item' added for this feature
-Jaffar starts with a full inventory for the sake of testing this feature