copy payload foe message clone.

Author: Oceania2018

src/Infrastructure/BotSharp.Abstraction/Conversations/Models/RoleDialogModel.cs

@@ -131,6 +131,7 @@ public static RoleDialogModel From(RoleDialogModel source,
             ToolCallId = source.ToolCallId,
             PostbackFunctionName = source.PostbackFunctionName,
             RichContent = source.RichContent,
+            Payload = source.Payload,
             StopCompletion = source.StopCompletion,
             Instruction = source.Instruction,
             Data = source.Data