There’s a sports betting court battle brewing, and people have been waiting for it for years. Right now, gambling on sports is legal in Nevada, where the Las Vegas casino sports books hum with activity under the glow of giant boards that show the point spreads. Just about everywhere else, it’s a black market, right down to the office football pool. Now, however, New Jersey wants a piece of the action — and it’s waging that they could reshape sports betting across the country. At stake is the staggering amount of money, up to $500 billion by some estimates, that…