rdp: add ability to forward reply to the client request
    
    In cases where the InfoPipe servers just as a middle-man between
    the DataProvider and a client we can simply forward the reply
    reducing amount of coded needed in the InfoPipe.
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>