The next designer handbag you buy is less likely to bear a “Made in China” label.Fashion companies, eager to diversify their supply chains, were already expanding into production sites in Southeast Asia as alternatives to China. Then the trade war happened.Now, with tariffs on products such as Chinese handbags set to rise, nations like Cambodia and Vietnam are looking more attractive than ever for consumer-goods makers such as Steven Madden Ltd. and Tapestry Inc.’s Coach.