An Open-label Extension Study to Evaluate Long-term Efficacy and Safety of Odevixibat (A4250) in Children with Biliary Atresia. Detailed Description: This is a Phase 3, multi-center, open-label extension study to evaluate the long-term efficacy and safety of odevixibat in patients with Biliary Atresia (BA). Patients who completed treatment in the A4250-011 BOLD study and meet