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/Components/Body/Behavior/HeartBehaviorComponent.cs

@@ -0,0 +1,33 @@
+using Content.Shared.GameObjects.Components.Body.Behavior;
+using Content.Shared.GameObjects.Components.Body.Networks;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Body.Behavior
+{
+    [RegisterComponent]
+    [ComponentReference(typeof(SharedHeartBehaviorComponent))]
+    public class HeartBehaviorComponent : SharedHeartBehaviorComponent
+    {
+        private float _accumulatedFrameTime;
+
+        public override void Update(float frameTime)
+        {
+            // TODO BODY do between pre and metabolism
+            if (Mechanism?.Body == null ||
+                !Mechanism.Body.Owner.HasComponent<SharedBloodstreamComponent>())
+            {
+                return;
+            }
+
+            // Update at most once per second
+            _accumulatedFrameTime += frameTime;
+
+            // TODO: Move/accept/process bloodstream reagents only when the heart is pumping
+            if (_accumulatedFrameTime >= 1)
+            {
+                // bloodstream.Update(_accumulatedFrameTime);
+                _accumulatedFrameTime -= 1;
+            }
+        }
+    }
+}