By Jose Torres VILLA COMALTITLAN (Reuters) – Thousands of migrants and asylum seekers moved slowly north across the southern Mexican state of Chiapas on Tuesday in a caravan hoping to reach the U.S. border, one day before top U.S. officials planned to visit Mexico to discuss migration. On Wednesday, Secretary of State Antony Blinken and Homeland Security chief Alejandro Mayorkas will visit Mexico to meet with Mexican President Andres Manuel Lopez Obrador. The officials will discuss “unprecedented irregular migration in the Western Hemisphere and identify ways Mexico and the United States will …