Actor state types for IPC actors.

[adlrocha]

Background

In the MVP of IPC, the IPC actors were targeting Filecoin's Legacy-VM. Consequently, the definition of all their params and their state were defined as Go types within the code base. Our newly implemented IPC actors targeting the FVM are written in Rust and through the process of re-writing them some parameters and state types have changed slightly. Also, the fact that we are now using Rust for the actor implementations implies that we need to ensure that the CBOR serialization used for the types is interoperable between Go and Rust

(note: by using cbor_gen we should get this by-design, however, silly mistakes can easily be introduced like not flagging a Vec<u8> to be serialized as a slice a bytes and Go trying then to deserialize it as []uint8 instead of []byte).

Goal

The goal of this issue is to create a package including all the state and params from the IPC actors to support their integration in the Lotus code base (so we can send messages with serialized params and interact seamlessly with the state of the FVM actors).

Tasks

Go types and cbor_gen serialization for:

• IPC basic primitives (mainly SubnetID and IPCAddress)
• subnet-actor params and state types.
• ipc-gateway params and state types.

[adlrocha]

A first pass over all the types and some auxiliary methods required (at the time of writing) to interact from Go with the actors have been implemented in this repo: https://github.com/consensus-shipyard/go-ipc-types. Refer to that repo for updates and additional issues regarding IPC Go types.