🕵️ Investigate in places where exceptions are being caught in the Azure Service bus message router

[stijnmoreels]

• An unexpected exception during message routing is something else then a message for which the MessageRouter can't find a MessageHandler ?

• The catch block around the single message processing: does this catch the exceptions that might be thrown by the MessageHandler's implementation ? It seems that this is already handled somewhere else. If so, I think we can indeed remove that catch block.

Originally posted by @fgheysels in #453 (comment)

[fgheysels]

This issue has been created to review the exception throwing and handling in Arcus.Messaging and see if we can simplify it a bit.