Expose itemPayload ID.

Otter had to reflect it.

Dalamud/Game/Text/SeStringHandling/Payloads/ItemPayload.cs

@@ -72,6 +72,12 @@ namespace Dalamud.Game.Text.SeStringHandling.Payloads
             }
         }
 
+        /// <summary>
+        /// Gets the raw item ID of this payload.
+        /// </summary>
+        [JsonIgnore]
+        public uint ItemId => this.itemId;
+
         /// <summary>
         /// Gets the underlying Lumina Item represented by this payload.
         /// </summary>