Largely erased from classical music history because he was biracial, the 18th-century French Caribbean violinist and composer Joseph Bologne wrote concertos, sonatas and symphonies. But “Chevalier,” a highly fictionalized account of Bologne’s life, understandably concentrates on his opera “Ernestine.” The movie itself has the virtues and vices of opera: It’s grand, sweeping and lavishly appointed, […]