Enabling storage independent of consensus

[adlrocha]

Storage features are independent from the consensus in Builder Net. While storage will still be verified, and we will keep all on-chain storage-specific features operating seamlessly (WindowPoSt, verified storage, storage and retrieval deals, miner slashing, etc.), the power table won't influence in any way the validation of new blocks.

SPs in BuilderNet will be able to run an SP (by running the lotus-miner process) without having to be a validator in the network. In order to completely decouple the storage from the conensus we need to:

• Disable WinningPoSts and block proposal from lotus-miner.
• Ensure the support of WindowPoSts and miner slashing.
• Support the onboarding of new storage, storage and retrieval deals.
• Add a reward interface to allow the implementation of different reward strategies (i.e. the distribution of rewards for Mir may differ slightly to how is currently done in Filecoin).

[adlrocha]

Available in spacenet. WinningPoSt is disabled when Mir consensus is used, and fake randomness is used as for FVM and the proofs to avoid requiring 1s randomness (or reusing drand beacons). WindowsPoSt are still periodically required to verify storage by lotus-miner. lotus-miners are no longer allowed to propose new blocks.