Playlist, Legacy Recordings’ series of single-disc anthologies spotlighting “The Hits plus the Fan Favorites,” keeps on rollin’ with a new, typically eclectic group of artists covering a wide swath of genres and styles. Today, May 21, Legacy releases volumes in the series dedicated to the best of R&B (Diana Ross, Donna Summer), pop (Billy Ocean), country-and-western (Chet Atkins, Patty Loveless, Restless Heart, Mindy McCready), Latin jazz (Tito Puente) and the many strains of rock