[Nakamoto] Update stacks-signer to check if a vote round has failed and trigger a new DKG round if it has

[jferrant]

Currently stacks-signers assume that a DKG round will be successful after they have broadcast their vote. However, a signer need to check if a vote failed for a specific round and trigger a DKG round if it has. (this occurs when the number of votes received by weight exceeds the threshold and we still have no approved key)