[Nakamoto] Associate signer_bitvec with reward_set signers

[zone117x]

A signer_bitvec property was added to /new_block in PR stacks-network/stacks-core#4526

We should be able to match this against the signers from the reward_set signer array by array index.

This should give us the option to provide API endpoint(s) with "signer performance data" like described at stacks-network/stacks-core#4257

a record of (signer) uptime and slot success rate.

[zone117x]

This issue is blocked for now because the signer bitvec data we receive from the core node doesn't yet indicate signer activity.