Add Visual3DBall scene (#4513)

* Add Visual3DBall scene which use visual observations with stacking

Author: Ruo-Ping (Rachel) Dong

Project/Assets/ML-Agents/Examples/3DBall/Prefabs/3DBall.prefab

@@ -279,17 +279,19 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   m_BrainParameters:
-    vectorObservationSize: 8
-    numStackedVectorObservations: 1
-    vectorActionSize: 02000000
-    vectorActionDescriptions: []
-    vectorActionSpaceType: 1
+    VectorObservationSize: 8
+    NumStackedVectorObservations: 1
+    VectorActionSize: 02000000
+    VectorActionDescriptions: []
+    VectorActionSpaceType: 1
   m_Model: {fileID: 11400000, guid: 20a7b83be6b0c493d9271c65c897eb9b, type: 3}
   m_InferenceDevice: 0
   m_BehaviorType: 0
   m_BehaviorName: 3DBall
-  m_TeamID: 0
-  m_useChildSensors: 1
+  TeamId: 0
+  m_UseChildSensors: 1
+  m_UseChildActuators: 1
+  m_ObservableAttributeHandling: 0
 --- !u!114 &114715123104194396
 MonoBehaviour:
   m_ObjectHideFlags: 0
@@ -302,8 +304,12 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: aaba48bf82bee4751aa7b89569e57f73, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  maxStep: 5000
+  agentParameters:
+    maxStep: 0
+  hasUpgradedFromAgentParameters: 1
+  MaxStep: 5000
   ball: {fileID: 1036225416237908}
+  useVecObs: 1
 --- !u!114 &1306725529891448089
 MonoBehaviour:
   m_ObjectHideFlags: 0
@@ -317,8 +323,7 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   DecisionPeriod: 5
-  RepeatAction: 1
-  offsetStep: 0
+  TakeActionsBetweenDecisions: 1
 --- !u!114 &1758424554059689351
 MonoBehaviour:
   m_ObjectHideFlags: 0
@@ -331,6 +336,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 3a6da8f78a394c6ab027688eab81e04d, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
+  debugCommandLineOverride: 
 --- !u!1 &1533320402322554
 GameObject:
   m_ObjectHideFlags: 0