Add utility AI (#806)

Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>
Co-authored-by: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>

Content.Server/AI/Utility/BehaviorSets/BehaviorSet.cs

@@ -0,0 +1,22 @@
+using System.Collections;
+using System.Collections.Generic;
+using Content.Server.AI.Utility.Actions;
+using Robust.Shared.Interfaces.GameObjects;
+
+namespace Content.Server.AI.Utility.BehaviorSets
+{
+    /// <summary>
+    /// AKA DecisionMaker in IAUS. Just a group of actions that can be dynamically added or taken away from an AI.
+    /// </summary>
+    public abstract class BehaviorSet
+    {
+        protected IEntity Owner;
+
+        public BehaviorSet(IEntity owner)
+        {
+            Owner = owner;
+        }
+
+        public IEnumerable<IAiUtility> Actions { get; protected set; }
+    }
+}