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!

Resources/Prototypes/Body/Mechanisms/human.yml

@@ -136,14 +136,13 @@
   - type: Mechanism
     size: 1
     compatibility: Biological
-    behaviors:
-    - !type:StomachBehavior
-      max_volume: 250
-      digestionDelay: 20
   - type: SolutionContainerManager
     solutions:
       stomach:
         maxVol: 250
+  - type: Stomach
+    maxVolume: 250
+    digestionDelay: 20
   # The stomach metabolizes stuff like foods and drinks.
   # TODO: Have it work off of the ent's solution container, and move this
   # to intestines instead.