ST. HELENA ISLAND, S.C. (AP) — Minnie “Gracie” Gadson claps her hands and stomps her feet against the floorboards, lifting her voice in a song passed down from her enslaved ancestors who were forced to work the cotton and rice plantations of the South Carolina Sea Islands. It’s a Gullah spiritual, and the 78-year-old singer is one of a growing group of artists and scholars trying to preserve these sacred songs and their Gullah Geechee culture for future generations. “I have a passion to sing