Change all of body system to use entities and components (#2074)

* Early commit

* Early commit 2

* merging master broke my git

* does anyone even read these

* life is fleeting

* it just works

* this time passing integration tests

* Remove hashset yaml serialization for now

* You got a license for those nullables?

* No examine, no context menu, part and mechanism parenting and visibility

* Fix wrong brain sprite state

* Removing layers was a mistake

* just tear body system a new one and see if it still breathes

* Remove redundant code

* Add that comment back

* Separate damage and body, component states, stomach rework

* Add containers for body parts

* Bring layers back pls

* Fix parts magically changing color

* Reimplement sprite layer visibility

* Fix tests

* Add leg test

* Active legs is gone

Crab rave

* Merge fixes, rename DamageState to CurrentState

* Remove IShowContextMenu and ICanExamine

Content.Server/GameObjects/EntitySystems/LungSystem.cs

@@ -0,0 +1,28 @@
+using Content.Shared.GameObjects.Components.Body.Behavior;
+using Content.Shared.GameObjects.EntitySystems;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects.Systems;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    [UsedImplicitly]
+    public class LungSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            UpdatesBefore.Add(typeof(SharedMetabolismSystem));
+        }
+
+        public override void Update(float frameTime)
+        {
+            base.Update(frameTime);
+
+            foreach (var lung in ComponentManager.EntityQuery<SharedLungBehaviorComponent>())
+            {
+                lung.Update(frameTime);
+            }
+        }
+    }
+}