[Consensus] Implement Consensus

[frisitano]

Overview

We must implement a consensus implementation that is production-ready. The current Consensus implementation is effectively a no-op.

[greged93]

Should we be checking anything other than the signature in the consensus implementation of the Rollup Node? My opinion is that all other rules other than the signature (which can't be checked by the execution layer) should live with the ScrollBeaconConsensus. What do you think?

[frisitano]

Yes, I agree we should check the signature. We will need to track the authorized signer from L1. Do we need to add a new event type for L1Watcher for a change of signer? Agreed, we validate the header in the reth consensus you linked.

[greged93]

Indeed, we need to track the system contract on the L1 and monitor for updates of the signer. Will include this in the PR.