Price of food depends on its nutritional capacity (#11752)

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
fixes https://github.com/space-wizards/space-station-14/issues/11464

Content.Shared/Chemistry/Reagent/ReagentPrototype.cs

@@ -84,6 +84,9 @@ namespace Content.Shared.Chemistry.Reagent
         [DataField("plantMetabolism", serverOnly: true)]
         public readonly List<ReagentEffect> PlantMetabolisms = new(0);
 
+        [DataField("pricePerUnit")]
+        public float PricePerUnit { get; }
+
         /// <summary>
         /// If the substance color is too dark we user a lighter version to make the text color readable when the user examines a solution.
         /// </summary>