WASHINGTON — A federal judge on Monday sided with an anti-abortion group in its challenge of a key birth control provision of the Obama administration’s health-care overhaul.The decision from U.S. District Judge Richard Leon adds to the legal debate surrounding the law’s requirement that contraceptives for women be included among a range of cost-free, preventive benefits offered to employees.The 29-page opinion held that March for Life could be exempt from the requirement, known as the contraceptive …