Fix ItemMapper whitelist mispredict when inserting or removing items (#29461)

* Fix ItemMapper whitelist mispredict when inserting or removing items

Makes the ItemMapper MapLayerData available on client so that the client
can predict whether an inserted/removed item changes the visibility of
a sprite layer.

* review

---------

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Shared/Storage/Components/SharedMapLayerData.cs

@@ -17,21 +17,21 @@ namespace Content.Shared.Storage.Components
     {
         public string Layer = string.Empty;
 
-        [DataField("whitelist", required: true, serverOnly: true)]
-        public EntityWhitelist ServerWhitelist { get; set; } = new();
+        [DataField(required: true)]
+        public EntityWhitelist? Whitelist { get; set; }
 
         /// <summary>
         ///     Minimal amount of entities that are valid for whitelist.
         ///     If it's smaller than minimal amount, layer will be hidden.
         /// </summary>
-        [DataField("minCount")]
+        [DataField]
         public int MinCount = 1;
 
         /// <summary>
         ///     Max amount of entities that are valid for whitelist.
         ///     If it's bigger than max amount, layer will be hidden.
         /// </summary>
-        [DataField("maxCount")]
+        [DataField]
         public int MaxCount = int.MaxValue;
     }