Shazam! brightened up the box office on Friday night, taking in $20.5 million on its way to a projected $51-54 million debut. It's an impressive haul for sure, but those numbers would also mark the lowest domestic opening for a movie in the DC Extended Universe, below Aquaman's $67 million. (To be fair, Aquaman then went on to gross more than a billion dollars worldwide.) Directed by David F. Sanberg (Annabelle: Creation), the film follows the 14-year-old Billy Batson (Asher Angel), a wayward kid in the foster system who is given the power to …