The “Avengers: Endgame” blockbuster kicked off the 2019 summer season with a seismic $2.34 billion box office bang.Here are synopses of other major movie openings:May“John Wick: Chapter 3 — Parabellum”: Assassin John Wick (Keanu Reeves), with a bounty on his head, must slay his way through a hoard of hitmen. Gorgeously rendered graphic gore.“The Sun is Also a Star”: Based on a YA …