DETROIT — Challenges are mounting for all-electric vehicle manufacturers Rivian Automotive and Lucid Group as the companies try to sell investors on a brighter, more profitable future to come. But things could get worse before they get better as both automakers are set to report third-quarter results this week, starting with Rivian after the bell Tuesday, followed by Lucid on Wednesday. Both "pure EV" companies are expected to report notable growths in revenue and narrowed adjusted earnings