feat: start of ability for miner to keep track of active signers bitvec

[hstove]

This PR adds two things:

• When a new Nakamoto block is formed, it starts with a BitVec of 1's with the length of the signer set.
• In the miner's coordinator thread, a next_signer_bitvec property is added. After a miner has collected all block responses from the signers, it updates this BitVec to match the signers who gave a response.

Note that, from a functional perspective, all this changes is that the length of the BitVec will match the signer's length. However, the BitVec will be all 1's, even if not all signers respond. Future work is required to construct a new block in the case that a block is rejected, and in that work we can use this next_signer_bitvec in that new block.

• Closes Construct signer_bitvec based on who signed each block #4558

[codecov]

Codecov Report

Attention: Patch coverage is 44.44444% with 40 lines in your changes are missing coverage. Please review.

Project coverage is 81.27%. Comparing base (c383bdd) to head (222d766).
Report is 2 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #4627      +/-   ##
==========================================
- Coverage   83.15%   81.27%   -1.89%     
==========================================
  Files         470      465       -5     
  Lines      332698   331526    -1172     
  Branches      317        0     -317     
==========================================
- Hits       276663   269444    -7219     
- Misses      56027    62082    +6055     
+ Partials        8        0       -8     

Files	Coverage Δ
stacks-common/src/bitvec.rs	92.05% <94.11%> (+0.34%)	⬆️
stackslib/src/chainstate/nakamoto/mod.rs	81.38% <0.00%> (-1.41%)	⬇️
testnet/stacks-node/src/nakamoto_node/miner.rs	0.00% <0.00%> (-83.47%)	⬇️
.../stacks-node/src/nakamoto_node/sign_coordinator.rs	0.00% <0.00%> (-77.09%)	⬇️

... and 79 files with indirect coverage changes

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[hstove]

Updated to add an error log based on a comment from Jude in d26e5a6. Requesting re-reviews

[hstove]

FYI - I fixed an issue with how the block was formed by the miner, which was breaking integration tests. I've also opened #4669 , which is the same code but off of develop. I'm happy to close this, but wanted to double check if that's the right move.

[hstove]

This PR is now based off of develop. Would love re-reviews please 😄