Implements item pricing, and piracy. (#8548)

* Start implementing item pricing.

* Flesh out prices a bit, add the appraisal tool.

* Add prices to more things.

* YARRRRRRR

* gives pirates an appraisal tool in their pocket.

* Makes the various traitor objectives valuable. Also nerfs the price of a living person, so it's easier to bargain for them.

* Address reviews.

* Address reviews.

Content.Shared/Materials/MaterialPrototype.cs

@@ -42,5 +42,11 @@ namespace Content.Shared.Materials
         [ViewVariables]
         [DataField("icon")]
         public SpriteSpecifier Icon { get; } = SpriteSpecifier.Invalid;
+
+        /// <summary>
+        /// The price per cm3.
+        /// </summary>
+        [DataField("price", required: true)]
+        public double Price = 0;
     }
 }