Log background errors coming from MessageReceiver

[mathewc]

When registering the ServiceBus MessageReceiver, we don't currently add an event handler to OnMessageOptions.ExceptionReceived. This means that any background exceptions (e.g. MessageLockLostException) will be silently ignored.

We should add a handler for both v1 and v2.

We've had several cases recently where locks were being lost but the absence of logs it hard to diagnose. E.g.:

#1697