Function send_handshake_message

async fn send_handshake_message(
    context: &Context,
    invite: &QrInvite,
    chat_id: ChatId,
    step: BobHandshakeMsg,
) -> Result<()>

Sends the requested handshake message to Alice.

Same as BobState::send_handshake_message but this variation allows us to send this message before we create the state in BobState::start_protocol.