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/Mobs/HumanoidAppearanceComponent.cs

@@ -1,4 +1,7 @@
+using Content.Shared.GameObjects.Components.Body;
 using Content.Shared.GameObjects.Components.Mobs;
+using Content.Shared.Preferences;
+using Robust.Server.GameObjects;
 using Robust.Shared.GameObjects;
 
 namespace Content.Server.GameObjects.Components.Mobs
@@ -6,6 +9,44 @@ namespace Content.Server.GameObjects.Components.Mobs
     [RegisterComponent]
     public sealed class HumanoidAppearanceComponent : SharedHumanoidAppearanceComponent
     {
+        public override HumanoidCharacterAppearance Appearance
+        {
+            get => base.Appearance;
+            set
+            {
+                base.Appearance = value;
 
+                if (Owner.TryGetBody(out var body))
+                {
+                    foreach (var part in body.Parts.Values)
+                    {
+                        if (!part.Owner.TryGetComponent(out SpriteComponent sprite))
+                        {
+                            continue;
+                        }
+
+                        sprite.Color = value.SkinColor;
+                    }
+                }
+            }
+        }
+
+        protected override void Startup()
+        {
+            base.Startup();
+
+            if (Appearance != null && Owner.TryGetBody(out var body))
+            {
+                foreach (var part in body.Parts.Values)
+                {
+                    if (!part.Owner.TryGetComponent(out SpriteComponent sprite))
+                    {
+                        continue;
+                    }
+
+                    sprite.Color = Appearance.SkinColor;
+                }
+            }
+        }
     }
 }