Creating the real Mystic Grill restaurant — named after the popular restaurant from the TV series “The Vampire Diaries” — won’t be cheap at a cost of $2.27 million, but the owners are hoping to get a low-interest loan from the state to cover at least a fraction of the cost. The long, inactive Covington Downtown Development Authority met for the first time in years Wednesday to offer support for the project by signing off on an initial project assessment — the first step in seeking a low-interest state loan for up to $250,000. The restaurant, located on the square in the historic C.S. Thompson