Convert StomachBehavior to a component/system + rejig body namespaces (#5249)

* Convert StomachBehavior to a component/system + rejig body namespaces

* test

* slightly more namespace changes

* remove

* Hello?????

* fuck you github test runner

* reviews

* oobsy!

Content.Client/Body/UI/BodyScannerBoundUserInterface.cs

@@ -1,5 +1,5 @@
 using System;
-using Content.Shared.Body.Scanner;
+using Content.Shared.Body.Components;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
 using Robust.Shared.GameObjects;