By Elizabeth Piper, Alistair Smout and William James LONDON (Reuters) -Rishi Sunak will become Britain’s first prime minister of colour on Tuesday 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 youngest leader in modern times – and its third 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 lasted…