A Phase 3, 2-Part, Randomized, Double-Blind, Placebo-Controlled Study (Part 1) and Open-Label Extension (Part 2) to Evaluate the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Omaveloxolone (BIIB141) in Participants With Friedreich's Ataxia Aged 2 to < 16 Years | Arctuva