HandsSystem Refactor (#38438)

* checkpoint

* pt 2

* pt... i forgot

* pt 4

* patch

* More test fixes

* optimization!!!

* the REAL hand system

* fix RetractableItemActionSystem.cs oversight

* the review

* test

* remove test usage of body prototype

* Update Content.IntegrationTests/Tests/Interaction/InteractionTest.cs

Co-authored-by: Tayrtahn <tayrtahn@gmail.com>

* hellcode

* hellcode 2

* Minor cleanup

* test

* Chasing the last of the bugs

* changes

---------

Co-authored-by: Tayrtahn <tayrtahn@gmail.com>

Content.Shared/Inventory/InventorySystem.Helpers.cs

@@ -16,12 +16,9 @@ public partial class InventorySystem
     {
         if (Resolve(user.Owner, ref user.Comp1, false))
         {
-            foreach (var hand in user.Comp1.Hands.Values)
+            foreach (var held in _handsSystem.EnumerateHeld(user))
             {
-                if (hand.HeldEntity == null)
-                    continue;
-
-                yield return hand.HeldEntity.Value;
+                yield return held;
             }
         }