CHATTANOOGA, Tenn. — German automaker Volkswagen said Monday its factory in Tennessee will be the focus of an $800 million investment in the company’s manufacturing of electric vehicles in North America, a sign of a growing push into the electric car market by European companies. Volkswagen made a couple of announcements that it will expand its plant in Chattanooga and create 1,000 jobs there as the factory gears up for electric vehicle production beginning in 2022.