Contractors using laborers from a Philadelphia church shelter to renovate Boston’s Copley Marriott Hotel are under investigation by Attorney General Martha Coakley for potential violations of wage laws and other worker protections, according to sources briefed on the matter. Coakley is investigating whether workers from Victory Outreach Church, which helps rehabilitate people with drug and alcohol problems, were brought into the state to be used as cheap labor for the renovation project. A Victory Outreach pastor, Joseph Bishop, said the church’s laborers were interviewed by investigators on Wednesday about the conditions of their employment at the Marriott, which is among the largest luxury hotels in Boston.