Actions System + UI (#2710)

Co-authored-by: Vera Aguilera Puerto <6766154+Zumorica@users.noreply.github.com>

Content.Shared/GameObjects/Components/Inventory/EquipmentSlotDefinitions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using Content.Shared.GameObjects.Components.Items;
 using JetBrains.Annotations;
 using Robust.Shared.Serialization;
 
@@ -26,7 +27,7 @@ namespace Content.Shared.GameObjects.Components.Inventory
         ///     Uniquely identifies a single slot in an inventory.
         /// </summary>
         [Serializable, NetSerializable]
-        public enum Slots
+        public enum Slots : byte
         {
             NONE = 0,
             HEAD,
@@ -148,6 +149,5 @@ namespace Content.Shared.GameObjects.Components.Inventory
             "Hands_left",
             "Hands_right",
         };
-
     }
 }

Content.Shared/GameObjects/Components/Inventory/SharedInventoryComponent.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Interfaces.Reflection;
 using Robust.Shared.IoC;
 using Robust.Shared.Serialization;
@@ -47,6 +48,10 @@ namespace Content.Shared.GameObjects.Components.Inventory
             InventoryInstance = DynamicTypeFactory.CreateInstance<Inventory>(type);
         }
 
+        /// <returns>true if the item is equipped to an equip slot (NOT inside an equipped container
+        /// like inside a backpack)</returns>
+        public abstract bool IsEquipped(IEntity item);
+
         [Serializable, NetSerializable]
         protected class InventoryComponentState : ComponentState
         {