We owe an awful lot to Arrow. This is, after all, the first show that believed in the idea that would eventually become the CW superhero universe. If you love The Flash or Legends of Tomorrow or Black Lightning or Supergirl, if you’re psyched that Batwoman has a pilot order or you’re looking forward to the insanity that will undoubtedly be the “Crisis on Infinite Earths” crossover this Fall; well, you basically have Arrow to thank for it. And 150 episodes later, the show feels as vibrant and necessary as it ever has. “Emerald Archer” not only takes …