By Steve Nesius and Steve Gorman CAPE CANAVERAL, Fla. (Reuters) – NASA’s next-generation moon rocket began a highly anticipated, slow-motion journey out of its assembly plant en route to the launch pad in Florida on Thursday for a final round of tests in the coming weeks that will determine how soon the spacecraft can fly. Rollout of the 32-story-tall Space Launch System (SLS) rocket and its Orion crew capsule marks a key milestone in U.S. plans for renewed lunar exploration after years of setbacks, and the public’s first glimpse of a space vehicle more than a decade in development. The proces…