Create helper decorators for decoding/handling payloads

[EnriqCG]

Decoding a payload into a JSON object requires the following extra code on every single controller.

@Consume('queueName')
function handleCreatedEvent(content: string) {
  const eventData = JSON.parse(content)
  // do something with the eventData object
}

Eventually, I'd like to implement a decorator that decodes the JSON payload automatically and potentially runs validation checks (with Data Transfer Objects) against it. NestJS already provides something similar for their HTTP controllers:

NestJS Implementation with HTTP

@Get('/')
function findAll(@Body() payload: payloadDTO) {
  // do something with `payload` already decoded into a JS object
}

What I want to achieve

@Consume('queueName')
function handleCreatedEvent(@EventPayload() payload: payloadDTO) {
  // do something with the payload object
}

[EnriqCG]

Moving this to milestone Version 1.1.