If we are to trot out the “supergroup” trope — more marketing schlock than anything — may all supergroups be like Fire and Water. In 2019, pianist Myra Melford, who was raised in Evanston and studied with members of the South Side-born Association for the Advancement of Creative Musicians (AACM), gathered other like-minded mavericks for a 2019 gig at the New York venue The Stone. Joining her were guitarist Mary Halvorson, saxophonist Ingrid Laub…