A powerful, shapeshifting teenage girl and a disgraced knight-in-training suspected of killing a beloved queen are at the heart of “ Nimona,” a vibrant and irreverent animated adventure set in a futuristic fantasy kingdom. It is a familiar story — a society governed by ancient rules and a crippling fear of outsiders — even by recent Netflix animation standards (see “The Sea Beast”). But “Nimona” is wrapped in new, exciting packaging with a wildly fun soundtrack featuring the likes of Metric, Dope Saint Jude and Judas Priest, LGBTQ+ themes that aren’t clumsily subtle, and charismatic lead voice actors in Chloë Grace Moretz and Riz Ahmed.