Scientists at a California company reported yesterday that they had created the first mature cloned human embryos from single skin cells taken from adults, a significant advance toward the goal of growing personalized stem cells for patients suffering from various diseases. Creation of the embryos — grown from cells taken from the company’s chief executive and one of its investors — also offered sobering evidence that few, if any, technical barriers may remain to the creation of cloned babies. That reality could prompt renewed controversy on Capitol Hill, where the debate over human cloning has died down of late.