explore how to handle `reply` operation in code generation

[derberg]

example from Slack and Hopscotch/Postman (one of these 2) has an operation that also has reply operation. This means that given application, whenever gets a message or sends a message, sends or receives a reply. We need to generate code that support is.

so for example in Slack, whenever you get a regular event, you need to reply with envelopeId. We need a code generated that will for example for client not only read an incomming message and allow you to write business logic for it, but also gives you an easy to use function to send a reply