Get ready to be reunited with the Targaryens, because HBO’s “Game of Thrones” spinoff series is quickly approaching. “House of the Dragon,” the highly anticipated prequel, released the full trailer for the new series on July 20, and it’s jam-packed with political intrigue, frightening fights, and, of course, dragons. The trailer previews the series’ main conflict: who will succeed King Viserys I (Paddy Considine) on the Iron Throne? He could pick his daughter Princess Rhaenyra (Emma…