By Elizabeth Piper, Alistair Smout and William James LONDON (Reuters) – Rishi Sunak will become Britain’s youngest prime minister in modern times after he won the race to lead the Conservative Party, tasked with steering a deeply divided country through an economic downturn set to leave millions of people poorer. One of the wealthiest politicians in Westminster, Sunak, 42, will become the country’s first leader of colour – and its third prime minister in less than two months – as he takes over during one of the most turbulent eras in British political history. He replaces Liz Truss, who only l…