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/Combat/TargetHealthCon.cs

@@ -11,7 +11,7 @@ namespace Content.Server.AI.Utility.Considerations.Combat
         {
             var target = context.GetState<TargetEntityState>().GetValue();
 
-            if (target == null || !target.TryGetComponent(out IDamageableComponent damageableComponent))
+            if (target == null || target.Deleted || !target.TryGetComponent(out IDamageableComponent damageableComponent))
             {
                 return 0.0f;
             }