Vote for Notarized Blocks during Replication

[samliok]

Keep Track of highestFinalizedSeqObserved and highestNotarizedSequenceObserved. This way we can broadcast our votes for notarizations during replication(if we know the sequence has not been finalized yet).

[yacovm]

While we can vote on notarized blocks while replicating, that's not a complete solution as the network may still drop our votes and we end up finishing the replication and there will still be a tail of notarized but not finalized blocks.