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.Shared/GameObjects/Components/Body/Part/BodyPartExtensions.cs

@@ -0,0 +1,37 @@
+#nullable enable
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Content.Shared.GameObjects.Components.Body.Part.Property;
+
+namespace Content.Shared.GameObjects.Components.Body.Part
+{
+    public static class BodyPartExtensions
+    {
+        public static bool HasProperty(this IBodyPart part, Type type)
+        {
+            return part.Owner.HasComponent(type);
+        }
+
+        public static bool HasProperty<T>(this IBodyPart part) where T : class, IBodyPartProperty
+        {
+            return part.HasProperty(typeof(T));
+        }
+
+        public static bool TryGetProperty(this IBodyPart part, Type type,
+            [NotNullWhen(true)] out IBodyPartProperty? property)
+        {
+            if (!part.Owner.TryGetComponent(type, out var component))
+            {
+                property = null;
+                return false;
+            }
+
+            return (property = component as IBodyPartProperty) != null;
+        }
+
+        public static bool TryGetProperty<T>(this IBodyPart part, [NotNullWhen(true)] out T? property) where T : class, IBodyPartProperty
+        {
+            return part.Owner.TryGetComponent(out property);
+        }
+    }
+}