NEW YORK -- Like many of those involved in the making of “Ma Rainey’s Black Bottom,” it’s not easy for Viola Davis to summarize what playwright August Wilson has meant to her except to answer, “Everything.”Davis' first stage role was in Wilson’s “Joe Turner’s Come and Gone.” She made her Broadway debut in his “Seven Guitars” and won a Tony for “King Hedley II.” After playing Rose on Broadway in Wilson’s “Fences,” she reprised the role in Denzel Washington’s 2016 film, winning her an Oscar.