CORTINA D'AMPEZZO, Italy — Mikaela Shiffrin, Aleksander Aamodt Kilde, Petra Vlhova, Alexis Pinturault, Corinne Suter. All five former overall World Cup ski champions or Olympic gold medalists have been involved in severe crashes during races over the past 15 days. And they’re not the only ones. Marco Schwarz, a former…