China has made your iPhone, your Nikes. Now, it wants to grow your cannabis. Two of China’s 34 regions are quietly leading a boom in cultivating cannabis to produce cannabidiol, or CBD, the nonintoxicating compound that has become a consumer health and beauty craze in the United States and beyond. They are doing so even though cannabidiol has not been authorized for consumption in China, a country with some of the strictest drug-enforcement policies in the world. “It has huge potential,” said Tan Xin, the chairman of Hanma Investment Group, which in 2017 became the first company to receive permission to extract cannabidiol here in southern China. The chemical is marketed abroad.