Add inventory and pickup components with associated resources and presenters

Code/Presenters/GamePresenter.cs

@@ -10,6 +10,7 @@ using GameCore.ECS;
 using GameCore.ECS.Interfaces;
 using GameCore.Events;
 using GameCore.Input;
+using GameCore.Inventory;
 using GameCore.Movement;
 using Godot;
 
@@ -54,6 +55,8 @@ public partial class GamePresenter : Node
         _world.RegisterSystem(new JumpSystem());
         
         _world.RegisterSystem(new AttributeSystem());
+        _world.RegisterSystem(new PickupSystem());
+        _world.RegisterSystem(new InventorySystem(_world));
         
         _world.RegisterSystem(new WeaponSystem());
         _world.RegisterSystem(new ProjectileSystem());