Add autoReply Flag to new HSD conversations

https://wphelpscout.com//developer.helpscout.net/help-desk-api/conversations/create/ “The ‘autoReply’ request parameter enables auto replies to be sent when a conversation is created via the API. When ‘autoReply’ is set to true, an auto reply will be sent as long as there is at least one ‘customer’ thread in the conversation.”