fix(f3): send the last gpbft message for each new participant

[Stebalien]

Proposed Changes

Send the last gpbft message for each new participant.

Otherwise, we can get into a situation where everyone is waiting for the next round to participate, but we'll never get there because not enough participants acted in the current round.

Checklist

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• Tests exist for new functionality or change in behavior
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[Stebalien]

I'm going to write an itest where:

1. One node participates from the beginning.
2. Later, all the other nodes start participating.

[Stebalien]

I'm going to have to refactor a few things to make this testable. I'd prefer to merge this as-is and merge the test later after the refactor.

[Kubuxu]

Change SGWM but itests seem unhappy.

[Stebalien]

The tests have been failing across all the F3 PRs regardless.