Just when you thought there'd be no Marvel's Avengers adventures in 2020, The Simpsons step in to deliver an epic, superheroic, cinematic spectacular ... on the small screen. In an upcoming episode of the long-running animated sitcom, new parent company Disney will lend talent from its other subsidiary, Marvel's MCU, as guest stars on Sunday's new episode "Bart the Bad Guy." Arriving almost a year after Avengers: Endgame, this half-hour centers on the two-part Vindicators: Crystal War film event of the year decade epoch. (And no, those Vindicators aren't the same ones from …