Issue statement: when user requests eth_simulateV1 to return full
transaction objects, these objects always had an empty `from` field. The
reason is we lose the sender when translation the message into a
types.Transaction which is then later on serialized.
I did think of an alternative but opted to keep with this approach as it
keeps complexity at the edge. The alternative would be to pass down a
signer object to RPCMarshal* methods and define a custom signer which
keeps the senders in its state and doesn't attempt the signature
recovery.