Allow Sending Raw Messages

[ghost]

When processing a message sent from one service ("original sending bus") to another ("original destination") fails, the message is marked as poison and, if configured, will end up in a special "dead letter queue" ("dlq").

We would like to be able to consume those messages and re-send them to their "original destination" - meaning - re-enqueueing them into their original destination queue.

Currently, when sending a message, Grabbit is setting headers that match the sending bus.

In order to restore the original flow, we need to add an "impersonation" ability, by adding headers that match to the original sending bus.

Meaning, allowing setting the headers manually - by allowing to send raw messages.