Refactor serialization copying to use source generators (#19412)

Content.Server/Labels/Label/Components/PaperLabelComponent.cs

@@ -6,7 +6,7 @@ namespace Content.Server.Labels.Components
     ///     This component allows you to attach and remove a piece of paper to an entity.
     /// </summary>
     [RegisterComponent]
-    public sealed class PaperLabelComponent : Component
+    public sealed partial class PaperLabelComponent : Component
     {
         [DataField("labelSlot")]
         public ItemSlot LabelSlot = new();