message: add clone for making copying easily
diff: @@ -13,7 +13,7 @@ pub mod ref_fvm {
  use fvm_shared::message::Message;
  /// Represents a wrapped message with signature bytes.
  - #[derive(Debug, Serialize_tuple, Deserialize_tuple)]
  + #[derive(Debug, Serialize_tuple, Deserialize_tuple, Clone)]
  pub struct SignedMessage {
  pub message: Message,
  pub signature: Signature,
  