Reneé Rapp is having quite a January.Just this month, the actress/singer celebrated her 24th birthday, starred in the box office smash “Mean Girls” and will serve as the musical guest on NBC’s “Saturday Night Live” alongside host Jacob Elordi on Saturday, Jan. 20.While that may seem like a lot, she’s just getting started.This year, Rapp is slated to headline at a whopping five (!) U.S.