Added trashSentMessageByAckData API command

For a while the msgid was not stored in the sent table. Current API commands only allow deletion of messages using msgid. I have added the trashSentMessageByAckData.API command which will allow deletion of sent messages using ackdata.

My intention of this commit is to help maintain backwards compatibility, allowing older sent messages to be deleted. However, I believe the preferred method of deleting messages should be done using msgid. Therefore, perhaps this API command should only be used as a "last resort".

Another benefit of using trashSentMessageByAckData is that an outgoing message can be "canceled". In other words, the message can be deleted while it is still in the PoW phase.