Implement StorageButton on HandsGUI and click empty hand to swap… (#517)

Also moved duplicate sprite view code to ItemSlotManager

Content.Shared/GameObjects/Components/Items/SharedHandsComponent.cs

@@ -27,17 +27,32 @@ namespace Content.Shared.GameObjects
     }
 
     /// <summary>
-    /// A message that activates the inhand, presumed for now the activation will occur only on the active hand
+    /// A message that calls the use interaction on an item in hand, presumed for now the interaction will occur only on the active hand.
     /// </summary>
     [Serializable, NetSerializable]
-    public class ActivateInhandMsg : ComponentMessage
+    public class UseInHandMsg : ComponentMessage
     {
-        public ActivateInhandMsg()
+        public UseInHandMsg()
         {
             Directed = true;
         }
     }
 
+    /// <summary>
+    /// A message that calls the activate interaction on the item in Index.
+    /// </summary>
+    [Serializable, NetSerializable]
+    public class ActivateInHandMsg : ComponentMessage
+    {
+        public string Index { get; }
+
+        public ActivateInHandMsg(string index)
+        {
+            Directed = true;
+            Index = index;
+        }
+    }
+
     [Serializable, NetSerializable]
     public class ClientAttackByInHandMsg : ComponentMessage
     {