Added enable_memory flag to chatbot/v3

Added enable_memory flag to chat_settings body parameter of https://api.exh.ai/chatbot/v3/response endpoint. This flag determines whether the long-term memory feature is used.

If it's set to True or not provided, and both bot_profile.id and user_profile.id are also provided, the service will store and utilize memory of the conversation. If it's set to False, no memory of past events beyond the current context will be available. For more details, refer to the documentation.