The pea soup fog and steady rain in the mountains outside of Palms Springs, California, are making it hard to figure out the character of the 2022 Mercedes-Benz AMG SL. With its new 2+2 layout, is the SL now a Porsche 911 competitor? Is it the lovechild of a C-Class cabriolet and an AMG GT roadster? Or do its soft top and small rear seat simply…