Trade, Taiwan and global tensions will likely top President Donald Trump’s agenda when he travels to China next week for a two-day summit. But as he speaks with President Xi Jinping and other Chinese Communist Party officials, he should also make a point of directly addressing the Chinese people.   That’s what President Ronald Reagan did in 1984, when he delivered a historic speech to students at Fudan University in Shanghai. Reagan set out to “introduce America” to those young minds — and such a mission is as important today as it was then, to counter Beijing’s narrative control and...