Create endpoint to return the message status

The endpoint accepts message id and return if the message is gone (already sent) or if it's still waiting for delivery.

Request:

POST /v1/message/status
{
  "messageId":"xxx"
}

• Response: 404 Not Found - if message is already delivered
• Response: 200 OK - if message is still waiting for delivery and can be delivered by PCM

HTTP 200
{
  "messageId":"xxx"
}