Stefon Diggs was asked straight-up if he plans on proposing to Cardi B ... and he admitted an engagement is "maybe" on the table -- but he's got a different ring on his mind first. The New England Patriots star took part in Opening Night at the Super Bowl on Monday ... and one reporter applied pressure on whether he intends to marry the "WAP" artist after he handles business on Feb. 8 against the Seattle Seahawks. "It's on the agenda maybe," Diggs said with a smile. "Right? Right? I gotta get