LAS VEGAS — Visitors to this city are assaulted by noise, be it the bells and whistles of the slot machines or the drilling and hammering of construction. The usual cacophony was exacerbated this week by a small but loud chorus of critics deriding Lexi Thompson’s participation in the Shriners Children’s Open, the third of the PGA Tour’s seven Fall Series events. Thompson, 28, an 11-time LPGA tour winner from Delray Beach, has dealt with naysayers since she was a 12-year-old golfing phenom.