June 15 (Reuters) - Kunlun Tech (300418.SZ) is planning a $400 million capital boost for a subsidiary expected to buy a stake in an artificial intelligence firm via a share issue, as Chinese tech firms ramp up efforts to develop rivals to Microsoft-backed OpenAI's ChatGPT. A global AI buzz kicked off by ChatGPT has spread to China, prompting a flurry of domestic companies including Alibaba and Huawei to announce similar projects and igniting venture funds and tech firms' interest in betting on startups that could be China's answer to OpenAI. Kunlun Tech said late on Wednesday its holding subsidiary Star...