By Ivelisse Rivera SAN JUAN, Puerto Rico (Reuters) – Hurricane Fiona strengthened to a powerful Category 4 storm on Wednesday as it headed toward Bermuda after carving a destructive path through the Dominican Republic and Puerto Rico, where most were without power and up to eight people might have died from the storm. After making landfall in Puerto Rico on Sunday, Fiona caused devastating flooding and landslides on the island and gathered steam as it barreled into the Dominican Republic and the Turks and Caicos Islands over the next two days. By Wednesday, Fiona was packing winds as high as 1…