BOSTON — General Electric is breaking ground on its new headquarters in a former candy factory in Boston.Jeff Immelt, GE's CEO, is expected to speak at the May 8 event, along with Massachusetts Governor Charlie Baker and Boston Mayor Marty Walsh.The multi-national conglomerate moved from Fairfield, Connecticut to temporary space in Boston's Seaport District last summer.The company is planning a new, $200 million campus consisting of three buildings on about 2.4 acres.