Allow multisigs to be set as miner owner address

[arajasek]

Fixes #5287

Motivation

Miners want to be able to set multisigs as their miner owner address. This currently fails if you use the set-owner command, because it assumes both the old and new owner address are accounts whose keys are in the Lotus wallet.

Changes

• Breaks the assumption that both the old and new owner address are accounts whose keys are in the Lotus wallet by changing the set-owner command to
  • take the sender of the ChangeOwnerAddress message as a param
  • not send both ChangeOwnerAddress messages within a single execution.
• Add a chain encode command as a util to encode params (does this not already exist somewhere? I couldn't find it?)
• Minor bugfix to lotus msig approve that makes it unusable when all optional params are provided.

Usage

• When the new owner is an account
  • Run lotus-miner actor set-owner --really-do-it <newOwner> <oldOwner>
  • Run lotus-miner actor set-owner --really-do-it <newOwner> <newOwner>. This command can be run from a different node or with a hardware wallet plugged in as needed.
• When the new owner is a multisig
  • Run lotus-miner actor set-owner --really-do-it <newOwner> <oldOwner> (assuming the old owner is an account)
  • Run lotus chain encode params --encoding=hex <minerAddress> 23 \"<newOwnerIdAddress>\", where 23 is the method number for ChangeOwnerAddress.
  • Run lotus msig propose --from=<newOwnerSigner> <newOwner> <minerAddress> 0 23 <params>, where params is the encoding outputted in the previous step.
  • (if needed) Run lotus msig approve --from=<newOwnerSigner> <newOwner> <transactionId> <proposingSigner> <minerAddress> 0 23 <params>.