[stacks-core] Update the stacker-db contract from the list of registered signers

[jferrant]

There should be a map of signer keys (public keys) to stacked stx in pox-4. Utilize this map to update the stacker-db config of the stacker-db instance to enable these signers to write to the appropriate slots. Note that we will need to sets of stacker-db slots. One for signers for cycle N, one for signers of cycle N+1.

[setzeus]

Pasting design doc that mentions this issue for reference: https://docs.google.com/document/d/1IFTaHjEGHJkdFiEfKNayfmD0UlseoXpVcoMgJv0VW1g/edit?usp=sharing

[setzeus]

Does #4125 change the requirements here?

[MarvinJanssen]

I feel like it does. Shall we schedule a discussion on it?

[MarvinJanssen]

This was addressed in #4263 and #4269. Signer sets are now written to a dedicated boot contact .signers instead of the PoX-4 contract.