National Republicans are rallying around a complete political unknown who stunned the party by winning a Michigan congressional primary over President Trump’s hand-picked candidate. Thomas Smith, a retired GM engineer who sells salsa that retails at Flint farmer’s markets, spent virtually nothing yet convincingly beat Trump-backed Amir Hassan — a US Navy vet and former federal law enforcement officer who raised $727,000. “He’s just as shocked as everyone was on election night,” a Smith campaign consultant told The Post. “He understands that this was not expected, but he also understands that people have spoken.” Smith won 50.4% of the vote...