CORONAVIRUS border closures and restrictions have stranded nearly 3 million migrants around the world who want to return home but cannot, the U.N. migration agency has said, adding some had been "warehoused" in unhygienic settings. The International Organization for Migration report is the most comprehensive to date on the issue, covering more than 100 countries. It includes only migrants who want to return but are unable to do so because of the COVID-19 restrictions -- such as seafarers stuck on decommissioned ships, miners or construction workers. "It should be clear that migrants can be returned home in a safe and…