Crooner George Strait, who's achieved a record 50 No. 1 country singles, has lately been inching toward the middle of the road, even as he hangs tight to his cowboy persona. But his new album, Honkytonkville, finds him back in the barroom, in touch with his jukebox roots. It's hard to imagine anyone doing it better. Behind the new songs that evoke the neon angst of Twitty and Jones, there's a singer of Sinatra-ish elegance, especially on ''Tell Me Something Bad About Tulsa,'' a shoo-in for No. 51.