Miner Transaction Replay on Bitcoin Reorg

[AshtonStephens]

Summary

Add a feature to the miner to replay Stacks transactions that were part of an invalid tenure due to a Bitcoin reorg.

Under Nakamoto, sortitions with a valid winner on the Bitcoin blockchain will yield a TenureChange that allows a new miner to produce blocks that the signers will sign, but a Bitcoin reorg can force the Stacks blockchain to reorganize because a Bitcoin block with a valid sortition can be orphaned itself, meaning that the orphaned tenures are now invalid. This ticket is to add a feature to the default Miner binary to have the miner replay transactions that were orphaned by a Bitcoin reorg to be included within the next tenure.

This ticket does not encompass including any kind of analysis on the validity of transactions, only prioritizing the replay of the transactions that were previously confirmed by a now invalid tenure.

Testing

• When a Bitcoin block is orphaned any Stacks transactions that were included in a tenure triggered by that orphaned block are replayed by the miner.

Success Criteria

• There's a written design for how the replay feature should behave
• The reference miner implementation includes the replay feature

[AshtonStephens]

Changed the wording to Miner, because that's what should be doing the replay, and the signer should potentially be enforcing it. This ticket is just for the reference miner implementation.