As well as her film about her own difficult teenage years, British director Lorna Tucker is probably best known for her documentaries on famous women with big personalities: Vivienne Westwood (Westwood: Punk, Icon, Activist), Katharine Hepburn (Call Me Kate) and Greta Garbo (Garbo: Where Did You Go?). Her latest subject, pianist Yuja Wang, is another high-achiever – but not someone with quite the same name recognition unless you’re a devotee of classical music, a field in which she is ranked among the very best alive. Wang certainly has a flamboyant…