Magic Johnson's pursuit of an NBA expansion franchise in Las Vegas has run into its most heavily financed rival yet, a group led by Basketball Hall of Famer Jerry Colangelo that says it is targeting as much as $13 billion in capital.The group, operating under the working name Las Vegas Jacks, went public on July 8 with $8 billion already lined up. Roughly $5 billion of that is committed, with another $3 billion formally indicated. Its stated ass…