NEW YORK, Aug 23 (Reuters) - A U.S. federal judge on Thursday rejected a claim by Britain's BT Group to have invented the basic means for navigating the Internet, in a case considered a test of who owns the basic Internet technology. BT Group, the former U.K. telecommunications monopoly known as British Telecom, had sued Prodigy Communications, a pioneering U.S. Internet service provider, demanding that Prodigy pay BT royalties for using hyperlink technology. In a decision issued late on Thursday, Judge Colleen McMahon of the U.S. District Court for the Southern District of New York denied BT Group's claim...