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/Utility/Considerations/Movement/TargetDistanceCon.cs

@@ -9,7 +9,7 @@ namespace Content.Server.AI.Utility.Considerations.Movement
         {
             var self = context.GetState<SelfState>().GetValue();
             var target = context.GetState<TargetEntityState>().GetValue();
-            if (target == null || target.Transform.GridID != self.Transform.GridID)
+            if (target == null || target.Deleted || target.Transform.GridID != self.Transform.GridID)
             {
                 return 0.0f;
             }