Made BehaviorType public and added the SetBehaviorType method (#3572)

* Made BehaviorType public and added the SetBehaviorType method

* Moving the comments around and making Setting the behaviorType to the same value do nothing

Author: vincentpierre

com.unity.ml-agents/Runtime/Agent.cs

@@ -363,6 +363,22 @@ public void GiveModel(
             m_Brain = m_PolicyFactory.GeneratePolicy(Heuristic);
         }
 
+        /// <summary>
+        /// Updates the type of behavior for the agent.
+        /// </summary>
+        /// <param name="behaviorType"> The new behaviorType for the Agent
+        /// </param>
+        public void SetBehaviorType(BehaviorType behaviorType)
+        {
+            if (m_PolicyFactory.m_BehaviorType == behaviorType)
+            {
+                return;
+            }
+            m_PolicyFactory.m_BehaviorType = behaviorType;
+            m_Brain?.Dispose();
+            m_Brain = m_PolicyFactory.GeneratePolicy(Heuristic);
+        }
+
         /// <summary>
         /// Returns the current step counter (within the current episode).
         /// </summary>

com.unity.ml-agents/Runtime/Policies/BehaviorParameters.cs

@@ -5,19 +5,31 @@
 
 namespace MLAgents.Policies
 {
+
+    /// <summary>
+    /// Defines what type of behavior the Agent will be using
+    /// - Default : The Agent will use the remote process for decision making.
+    /// if unavailable, will use inference and if no model is provided, will use
+    /// the heuristic.
+    /// - HeuristicOnly : The Agent will always use its heuristic
+    /// - InferenceOnly : The Agent will always use inference with the provided
+    /// neural network model.
+    /// </summary>
+    [Serializable]
+    public enum BehaviorType
+    {
+        Default,
+        HeuristicOnly,
+        InferenceOnly
+    }
+
+
     /// <summary>
     /// The Factory to generate policies.
     /// </summary>
     [AddComponentMenu("ML Agents/Behavior Parameters", (int)MenuGroup.Default)]
     internal class BehaviorParameters : MonoBehaviour
     {
-        [Serializable]
-        enum BehaviorType
-        {
-            Default,
-            HeuristicOnly,
-            InferenceOnly
-        }
 
         [HideInInspector]
         [SerializeField]
@@ -36,7 +48,7 @@ enum BehaviorType
         //   and will always have its default value
         // This field is set in the custom editor.
         #pragma warning disable 0649
-        BehaviorType m_BehaviorType;
+        internal BehaviorType m_BehaviorType;
         #pragma warning restore 0649
         [HideInInspector]
         [SerializeField]