FIP 29 - Beneficiary address for storage providers

[lemmih]

Issue summary

Checklist:

• [x] Are there any changes to the actor data structures that we need to be aware of?
• [x] Are there any changes to the network protocol?
• [x] Are there any changes to node behavior (eg. changes in block validation criteria, random number generation, etc)?
• [x] Are there any new magic numbers?

Other information and links

FIP: https://github.com/filecoin-project/FIPs/blob/master/FIPS/fip-0029.md

[LesnyRumcajs]

Beneficiary information in state

There will be a change to MinerInfo struct. We have it copied from builtin-actors. Perhaps it will be an opportunity to import it and reduce duplication. Otherwise, we can just copy the updated version.

Withdrawals to beneficiary

Internal in builtin-actors.

Setting the beneficiary address

Internal in builtin-actors.

Related PR: https://github.com/filecoin-project/builtin-actors/pull/496

There shouldn't be any consensus change. We should be good with updating the builtin-actors dependency and importing or copying the MinerInfo struct to Forest.

:warning: Tests :warning: Those structs are used only in our RPC API which is not covered by tests. It would be great to at least test that it works manually.