As India eases one of the world’s tightest coronavirus lockdowns, millions of migrant workers are struggling with a question that could determine both how quickly the country’s economy recovers and how widely the virus spreads: Stay put or go home? Self-employed people are allowed to resume work, and some factories and neighborhood shops have started to reopen, though at partial capacity. At the same time, the national rail company has set up special trains to help workers get back from crowded cities to their home…