The 6-year-old central character of “The Florida Project,” Moonee (Brooklynn Prince), is a modern-day Huck Finn. Left mostly to her own devices, she roams a colony of cheap motels, filled with budget tourists, transients and near-homeless families, along Florida’s Route 192 — the road to Disney’s Magic Kingdom.Full of cheek and mischief, the ebullient Moonee lives in the ironically, euphemistically and misleadingly named Magic Castle Motel. She shares a room in the lilac- and orchid-hued motor …