Spec. Leader Coin Evolution

Coin's now have a nonce
api to evolve coins: Coin.evolve() which evolves the coins nonce
LeaderProofs now have a evolved_commitment which are added to the set of eligible commitments.
LedgerState now maintains two sets of commitments:
- commitments_spend for commitments that are eligible for spending
- commitments_lead for commitments that are eligible for leading
LeaderProofs are coin commitments are verified against two sets, it's eligible if
- it's in the previous blockscommitments_to_lead ledger_state
- or it's in the the EpochState's stake distribution snapshot's spendable commitments.

logos-co / nomos-specs