Study protocol for type II hybrid implementation-effectiveness trial of strategies for depression care task-sharing in community health stations in Vietnam: DEP Project oleh Victoria Khanh Ngo, Thinh Toan Vu, Quan Anh Vu, Ryan McBain, Gary Yu, Ngoc Bao Nguyen, Hien Mai Thi Nguyen, Hien Thi Ho, Minh Van Hoang