InboundMessageEvent.data.payload does not expose autoresponse_type

[danclaroni]

If we want to process webhooks in nodejs for stop codes, we need this to be exposed. Your docs say the webhook event should have autoresponse_type on the payload object.

e.g. https://developers.telnyx.com/docs/messaging/messages/advanced-opt-in-out#how-can-i-programmatically-track-opt-out-behavior-in-my-application