MUSKETEER OF STEEL Moorpark High wrestler Brett Williamson, bottom, spars with assistant coach Richie Vaillancourt on Feb. 1. Williamson, a 4.25 GPA scholar athlete, also excels at football and field hockey. Photos by MICHAEL COONS/Acorn Newspapers Call Brett Williamson the Musketeer of Steel. Williamson, a Moorpark High sophomore, has earned his share of hardware from wrestling,