By Hritika Sharma BEIJING (Reuters) -Britain edged 2018 Olympic champions Sweden 12-11 in an extra end in a tense showdown on Friday to advance to the women’s curling gold-medal contest against surprise finalists Japan at the Winter Games on Friday. Twenty years after Rhona Martin skipped Britain to victory in Salt Lake City, the country are in the running to win two curling golds in Beijing after Eve Muirhead led her team to the final a day after Bruce Mouat guided the men’s rink into the final. Japan, who finished fourth in the standings, upset Switzerland at the National Aquatics Centre to …