“Josephine,” a gripping drama about a young girl who witnesses a brutal assault, was the toast of this year’s Sundance Film Festival. Not only did critics praise Channing Tatum and Gemma Chan for their performances as parents struggling to help their traumatized daughter, but the film won the festival’s audience and jury awards. It seemed like “Josephine” was destined to land at an established indie like Neon or A24 or, barring that, a streaming giant like Netflix. Instead, it wound up at