PARIS — Sarah Knafo is using the electoral race for Paris mayor as a springboard to build her profile as the rising star of France’s anti-immigration, libertarian right. The 32-year-old firebrand MEP is on track for a significant breakthrough in a city with a traditional aversion to the far right. If she can maintain that level of support — she’s currently polling at 12 percent — Knafo would be the first far-right candidate ever to make the second round in the City of Lights. The big question