By Sergio Goncalves and Catarina Demony LISBON (Reuters) -Portugal’s ruling Socialists looked set to win the most votes, and possibly an outright majority, in Sunday’s snap general election, exit polls showed, triggering celebrations in Prime Minister Antonio Costa’s election headquarters. The result, boosted by a higher than expected turnout despite the coronavirus pandemic, comes as a surprise after the Socialists had lost most of their advantage in recent opinion polls, and could signal a chance for Portugal to have a stable government, contrary to most expectations. As exit polls came out …