“It’s just that jazz ain’t cool anymore,” the sexy saxophonist is told in the new Amazon Prime dramatic feature “Sylvie’s Love.”But Viola Davis’ title character in Netflix’s “Ma Rainey’s Black Bottom,” disagrees: “Blues helps you get out of bed in the morning.”Who would have thought that one of the notable trends in filmed entertainment at this time would be an American art form born more than 120 years ago? Amid the stalled and rearranged film landscape of 2020, just as the Black Lives Matter