Zack Snyder never believed that his cut of “Justice League” would see the light of day. Although he’s officially credited as the director of the DC superhero mashup that hit theaters in the summer of 2017, he and his wife and producing partner Deborah Snyder had stepped down months earlier. Studio relations were strained and the pressure was getting to be too much, especially after the suicide of their 20-year-old daughter. Now four years later, his vision is finally finished and coming to HBO Max on Thursday, thanks to an extremely persuasive fan campaign and a streaming service in need of content. And this time, even the critics like it.