Add multi-layer in-hand and clothing support (#6740)

Content.Client/Hands/HandsComponent.cs

@@ -1,7 +1,7 @@
 using Content.Shared.Hands.Components;
 using Robust.Shared.Analyzers;
 using Robust.Shared.GameObjects;
-using Robust.Shared.IoC;
+using System.Collections.Generic;
 
 namespace Content.Client.Hands
 {
@@ -11,5 +11,10 @@ namespace Content.Client.Hands
     public sealed class HandsComponent : SharedHandsComponent
     {
         public HandsGui? Gui { get; set; }
+
+        /// <summary>
+        ///     Data about the current sprite layers that the hand is contributing to the owner entity. Used for sprite in-hands.
+        /// </summary>
+        public readonly Dictionary<HandLocation, HashSet<string>> RevealedLayers = new();
     }
 }