A Phase 2/3, Open-label, Historical-controlled, Single-arm, Multicenter Study to Evaluate the Efficacy, Pharmacokinetics, Pharmacodynamics, and Safety of Ravulizumab in Children and Adolescents With Aquaporin-4 Antibody Positive (AQP4-Ab [+]) Neuromyelitis Optica Spectrum Disorder (NMOSD) | Arctuva