When it comes to the Fourth of July, it’s all about outdoor activities. According to a survey by the National Retail Federation, nearly 70 percent of Americans plan to celebrate the holiday by holding or attending a cookout, barbecue or picnic. And local retailers are stocking up on items needed to make the outdoor festivities successful.“There will be lots of grilling, yep,” said Brenda Reid, a spokeswoman for Publix Supermarkets, which has several Forsyth County locations.