RINA CHANDRAN MIGRANT workers in Asia are being locked up and abandoned by employers even as countries ease coronavirus curbs, say human rights groups, which are calling for better housing and changes to visa laws. The warning came after more than a dozen workers from Myanmar were dumped by the roadside in Thailand this week following a ban on the movement of migrant workers in and out of certain areas because of a COVID-19 outbreak. In Singapore, where cramped dormitories were a virus hotspot, migrant workers are still largely confined to their rooms even as authorities have eased restrictions in…