ANDRE PAULTRE and SARAH MARSH A power struggle is brewing in Haiti as the man appointed prime minister shortly before the assassination of Haiti's president this week said he - not the acting premier - should lead the Caribbean nation and was forming a government to that effect. Ariel Henry, a neurosurgeon who was named prime minister by President Jovenel Moise on Monday, two days before Moise was killed by a squad of gunmen in his home in the capital, Port-au-Prince, said he was now the highest authority in Haiti, not interim Prime Minister Claude Joseph. "After the president's assassination,…