Although Vivian J.O. Barnes is still finishing graduate school in playwriting her show “Duchess! Duchess! Duchess!” was produced by Steppenwolf Theatre and is available online until Aug. 31.Directed by Weyni Mengesha, the play stars two wonderful Black actresses in a conversation between a Duchess (Sydney Charles) and a soon-to-be Duchess (Celeste M. Cooper) as they consider the pressure to fit in, toe the line, self-censor and adjust to a life of royalty.As the two women reflect upon the restrictions that are imposed — on …