Here’s a decadent double feature: Two movies about enticing cabaret singers in Germany, in different eras but with similarly destructive tendencies. First up, at 8 p.m. ET, is Bob Fosse’s superb 1972 movie musical starring Liza Minnelli and Joel Grey, about a Berlin nightclub and the slow but steady and unnerving encroachment of the Nazi Party. Then, at 10:15 p.m. ET, it’s The Blue Angel, from 1930, starring Marlene Dietrich – in her star-making role – as a singer w