Monitor Teleporter messages received to have corresponding sends

[minghinmatthewlam]

Context and scope
TeleporterMessenger receive messages should always have a corresponding send message from the origin chain of the message. Looking to create a monitor that alerts us if a Teleporter message was received without a corresponding send message.

Discussion and alternatives
When receiving Teleporter message, we should have information about which source chain sent the message, as well as the message ID. With that information, can we find the corresponding sendCrossChainMessage on source chain?

Open questions
What if the send was sent many blocks ago? How many blocks should/can we look back?
How about chains that have enough stake weight and want to just randomly add receive messages without a corresponding send? (like the incident drill)