HONG KONG, July 27 (Reuters) - The first person charged under Hong Kong"s national security law was found guilty on Tuesday of terrorism and inciting secession in a landmark case with long-term implications for how the legislation reshapes the city"s common law traditions. An alternative charge of dangerous driving causing grievous bodily harm was not considered. Former waiter Tong Ying-kit, 24, was accused of driving his motorcycle into three riot police while carrying a flag with the protest slogan "Liberate Hong Kong. Revolution of our times," which prosecutors said was secessionist.