A Multicenter, Open-Label Study Evaluating the Long-Term Safety, Tolerability, and Efficacy of Monthly Subcutaneous Administration of Fremanezumab for the Preventive Treatment of Episodic and Chronic Migraine in Pediatric Patients 6 to 17 Years of Age A Study of the Long-Term Safety, Tolerability, and Efficacy of Fremanezumab for Preventing Migraine in Pediatric Patients A Study to Test if Fremanezumab is Effective in Preventing Migraine in Children and Adolescents Long-Term Safety Study (Phase 3)