Farce, with its antic misunderstandings and confused identities, can polarize audiences. Spectators may either be exhilarated by the pandemonium or left cold. With Merry Wives: A Celebration of Black Joy and Vitality, the sole production of this summer’s Free Shakespeare in Central Park, playwright Jocelyn Bioh gambles that, after a year of societal strife, she can unify audiences by updating William Shakespeare’s rambunctious farce The Merry Wives of Windsor.