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/UseItemInInventoryOperator.cs

@@ -0,0 +1,46 @@
+#nullable enable
+using Content.Server.GameObjects.Components.GUI;
+using Content.Server.GameObjects.Components.Items.Storage;
+using Robust.Shared.Interfaces.GameObjects;
+
+namespace Content.Server.AI.Operators.Inventory
+{
+    /// <summary>
+    /// Will find the item in storage, put it in an active hand, then use it
+    /// </summary>
+    public class UseItemInInventoryOperator : AiOperator
+    {
+        private readonly IEntity _owner;
+        private readonly IEntity _target;
+
+        public UseItemInInventoryOperator(IEntity owner, IEntity target)
+        {
+            _owner = owner;
+            _target = target;
+        }
+
+        public override Outcome Execute(float frameTime)
+        {
+            // TODO: Also have this check storage a la backpack etc.
+            if (!_owner.TryGetComponent(out HandsComponent handsComponent))
+            {
+                return Outcome.Failed;
+            }
+
+            if (!_target.TryGetComponent(out ItemComponent itemComponent))
+            {
+                return Outcome.Failed;
+            }
+
+            foreach (var slot in handsComponent.ActivePriorityEnumerable())
+            {
+                if (handsComponent.GetItem(slot) != itemComponent) continue;
+                handsComponent.ActiveHand = slot;
+                handsComponent.ActivateItem();
+                return Outcome.Success;
+            }
+
+            return Outcome.Failed;
+        }
+    }
+}