CNBC's Jim Cramer explained why he thinks Alphabet's new iteration of its artificial intelligence platform, Gemini, could seriously challenge the dominance of OpenAI's ChatGPT."We have to recognize that Gemini's the biggest threat to ChatGPT we've seen so far. There's simply no two ways about it — Gemini's existential for OpenAI," he said. "The company, the emperor, better have…something to strike back, because otherwise the narrative will be that OpenAI has no clothes."Alphabet announced its new Gemini mod ...