Refactor body component to use slots instead of an army of dictionaries (#3749)

* Refactor body component to use slots instead of an army of dictionaries

* Update vox

* Replace static method call with extension

* Add setpart method, replace dispose with shutdown

* Fix tests, fix not listening to slot events when setting a part

Content.Server/Commands/Body/RemoveHandCommand.cs

@@ -42,7 +42,8 @@ namespace Content.Server.Commands.Body
                 return;
             }
 
-            var (_, hand) = body.Parts.FirstOrDefault(x => x.Value.PartType == BodyPartType.Hand);
+            var hand = body.GetPartsOfType(BodyPartType.Hand).FirstOrDefault();
+
             if (hand == null)
             {
                 shell.WriteLine("You have no hands.");