Define SignedMessage struct

[rllola]

I am using SignedMessage struct from the chainsafe library. Is there any plan to add it to the lib ? It would help with migration without breaking stuff.

See https://github.com/ChainSafe/forest/blob/main/vm/message/src/signed_message.rs#L13

[Stebalien]

Is there any reason you can't define it locally? SignedMessage isn't relevant to the FVM.

[Stebalien]

(no strong reason not to include it, we'd just rather not include anything we don't need (especially in shared) unless it makes everyone's lives significantly easier)

[rllola]

I am actually trying to define it locally but I have encounter an other issue for which I opened a PR (https://github.com/filecoin-project/ref-fvm/pull/446).

I don't have a strong reason to have it included beside helping migrating from chainsafe lib to this one. I believe Forest will need this too so instead of everyone having its own implementation having one in this standard lib would avoid issues I guess.

[raulk]

A few months later, we can confirm that this struct is not relevant or missed in ref-fvm; it's a client-specific type. An idea here would be for Forest to spin off its common types to an independent crate.