feat: rollback update

[0xng]

Description

This PR aims to update the message rollback implementation in the L2ToL2CrossDomainMessenger to match new practices.

Additional Questions

There's a necessity to have a way for relayExpire to know that the message not only originated from L2ToL2CrossDomainMessenger, but that it also originated within sendExpire. This is to avoid someone from expiring arbitrary hashes by calling sendMessage in the L2ToL2CrossDomainMessenger and then relaying the message to relayExpire. A way to do this is by setting the sender in sendExpire to an impossible account. I chose the L2ToL2CrossDomainMessenger address itself.

I was wondering whether a random account would be better, like 0xdead. My worry comes because this allows the path where the message created in sendExpire is not sent to relayExpire but to relayMessage, which would set the sender to the L2ToL2CrossDomainMessenger, and perhaps this could mess with contracts integrating with it.