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/Commands/OpenAHelpCommand.cs

@@ -1,6 +1,5 @@
 using System;
-using Content.Client.Administration;
-using Content.Shared.Body.Mechanism;
+ using Content.Client.Administration;
 using Robust.Client.Console;
 using Robust.Client.GameObjects;
 using Robust.Shared.Console;