Economic activity is gathering momentum in China, a raft of survey data showed this week, the latest sign that Beijing’s uncompromising approach to tackling the coronavirus pandemic is starting to pay dividends even as the U.S. shuts down swaths of its economy in a struggle to contain the virus. A private gauge of China’s service-sector activity, released Friday, surged in June to its highest level in more than a decade, as the easing of virus-control measures in most parts of the country drove consumer demand. The…