A Phase 2, Open-Label, Multicenter, Randomized Study to Evaluate Denikitug as Monotherapy or in Combination With Nivolumab or Chemotherapy in Participants With HER2-Negative, Unresectable, Recurrent, and/or Metastatic Gastric, Gastroesophageal Junction (GEJ), and Esophageal Adenocarcinomas | Arctuva