LONDON, Sep 21 : Andy Burnham once said he would refuse to meet Donald Trump.Now Britain's prime minister is about to hold his first meeting with the US president, with Ukraine and the soaring cost of conflict in the Middle East at the top of his agenda.US officials say the two leaders will hold talks on the sidelines of the United Nations General Assembly in New York. Burnham is set to address the annual gathering of world leaders on Tuesday, setting out his vision of Britain's place in an increasingly fractured world order.Advertisement Burnham's only other foreign trip since taking…