Add acceptance test to verify audit behavior for control messages

[andreasohlund]

This confirms that control messages are audited

[danielmarbach]

@andreasohlund When I said I think they are not, I was thinking about this code

NServiceBus/src/NServiceBus.Core/Pipeline/Incoming/DeserializeMessageConnector.cs

Lines 63 to 74 in 075d256

	// We need this check to be compatible with v3.3 endpoints, v3.3 control messages also include a body
	if (IsControlMessage(physicalMessage))
	{
	log.Debug("Received a control message. Skipping deserialization as control message data is contained in the header.");
	return Array.Empty<LogicalMessage>();
	}
	if (physicalMessage.Body.Length == 0)
	{
	log.Debug("Received a message without body. Skipping deserialization.");
	return Array.Empty<LogicalMessage>();
	}

but I guess I was wrongly assuming the audit context happens later which is incorrect as I now see

NServiceBus/src/NServiceBus.Core/Audit/InvokeAuditPipelineBehavior.cs

Line 23 in 075d256

var processedMessage = new OutgoingMessage(context.Message.MessageId, new Dictionary<string, string>(context.Message.Headers), context.Message.Body);