By Ritsuko Shimizu and Kane Wu TOKYO (Reuters) -Japan’s Seven & i Holdings has received a buyout proposal from a member of its founding Ito family, it said on Wednesday, a potential $58 billion white-knight bid as it weighs a rival offer from Canada’s Alimentation Couche-Tard The offer for Ito-Kogyo, a company linked to Vice President Junro Ito and a top shareholder in 7-Eleven owner, is non-binding and under review