Cesar Chavez, center, joins with United Farm Workers while demonstrating in New York, Oct. 10, 1969. An investigation by The New York Times found extensive evidence that the United Farm Workers co-founder groomed and sexually abused girls who worked in the movement. (John Sotomayor/The New York Times) By SARAH HURTES and MANNY FERNÁNDEZ Every year, thousands gather to celebrate Cesar Chavez, the labor leader who rose from the poverty of Arizona’s lettuce fields to build one of the most...