WINCHESTER — Swampscott resident Aidan Emmerich is hoping this is the year he finally breaks through and wins the big one. Last year, Emmerich reached the semifinals of the 117th Massachusetts Amateur, only to lose a close one, leaving what he described as a “sour taste in my mouth.” Friday, at Winchester Country Club, the Kernwood CC member turned sour to sweet and is one step closer to raising the champion’s Massachusetts Cup, narrowly defeati…