[Feature] Enable signing of future batch proposals

[vicsn]

🚀 Feature

Stress-tests show that we frequently don't sign future batch proposals because they're for a future round. We should investigate if we can get rid of this code:

-            // If the signed round is ahead of the peer's batch round, do not sign the proposal.
-            // Note: while this may be valid behavior, additional formal analysis and testing will need to be done before allowing it.
-            if signed_round > batch_header.round() {
-                bail!(
-                    "Peer ({batch_author}) proposed a batch for a previous round ({}), latest signed round: {signed_round}",
-                    batch_header.round()

[kaimast]

I can do some investigating, but, to my knowledge, it would not cause any problems.

However, we should put a bound on how far in the future a batch can be, so an attack that overloads a node with batch proposals is not possible.