Refactor standing to be ECS (#4142)

* Refactor standing to be ECS

E C S B A B Y

* DONE

* FIX IT FIX IT FIX IT

* IsDown event

* Change to methods

* Fixes

* Address some reviews

* Last of the Mohicans

* Final fixes

* Fix tests

Content.Server/Morgue/Components/MorgueEntityStorageComponent.cs

@@ -1,5 +1,4 @@
 #nullable enable
-using Content.Server.Standing;
 using Content.Server.Storage.Components;
 using Content.Shared.Body.Components;
 using Content.Shared.Directions;
@@ -9,6 +8,7 @@ using Content.Shared.Interaction.Helpers;
 using Content.Shared.Morgue;
 using Content.Shared.Notification.Managers;
 using Content.Shared.Physics;
+using Content.Shared.Standing;
 using Robust.Server.GameObjects;
 using Robust.Shared.Audio;
 using Robust.Shared.Containers;
@@ -51,7 +51,7 @@ namespace Content.Server.Morgue.Components
         {
             base.Initialize();
             Appearance?.SetData(MorgueVisuals.Open, false);
-            TrayContainer = ContainerHelpers.EnsureContainer<ContainerSlot>(Owner, "morgue_tray", out _);
+            TrayContainer = Owner.EnsureContainer<ContainerSlot>("morgue_tray", out _);
         }
 
         public override Vector2 ContentsDumpPosition()