The Babe's power built Yankee Stadium in the Bronx, but now his house is an antique in a supersonic age. The Yankees were being wooed by developers of a planned suburban superstadium in New Jersey, and traditionalists were shuddering. The Hackensack Yankees? The Garden State Bombers? But last week Governor Nelson Rockefeller approved a bond issue requested by Mayor John Lindsay that will permit New York City to purchase the stadium for $24,000,000. Fans will get escalators, new seats and a deck over the bleachers, and taxpayers will get more access roads and parking lots. The Yankees have promised to stay for 30 years. They may have the place to themselves, too, for the NFL Giants seem to already have one cleated foot in the Jersey marshes.