AI pickup changes (#1811)

* AI pickup changes

Eating and drinking isn't spammed anymore.
AI can do InRangeUnobstructed checks for item pickups.
AI can open drink cans.

AI littering to be coded.

* #nullable enable

* github's nullable fails are actively shortening my lifespan

* Use a const instead

So it's easier to find given the performance implications.

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Server/AI/Operators/Inventory/PickupEntityOperator.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using Content.Server.GameObjects.Components.GUI;
 using Content.Server.GameObjects.Components.Items.Storage;
 using Content.Server.GameObjects.EntitySystems.Click;
@@ -20,11 +21,9 @@ namespace Content.Server.AI.Operators.Inventory
             _target = target;
         }
 
-        // TODO: When I spawn new entities they seem to duplicate clothing or something?
         public override Outcome Execute(float frameTime)
         {
-            if (_target == null ||
-                _target.Deleted ||
+            if (_target.Deleted ||
                 !_target.HasComponent<ItemComponent>() ||
                 ContainerHelpers.IsInContainer(_target) ||
                 !InteractionChecks.InRangeUnobstructed(_owner, _target.Transform.MapPosition))