MAPUTO, Mozambique — Amnesty International Wednesday accused Mozambique’s government forces of torturing suspected members of an Islamist insurgency in the country’s northern Cabo Delgado province, as well as “possible extrajudicial executions” and “discarding a large number of corpses into apparent mass graves.” “This behavior flouts fundamental principles of humanity. The abuses attributed to the group known as Al-Shabaab can never …