Volunteers at the Palestine Red Crescent Society stay on the phone with a 6-year-old girl who gets trapped in a car in war-torn Gaza. Incorporating real-life elements that are as difficult to witness as they are impossible to forget, Kaouther Ben Hania’s “The Voice of Hind Rajab” (2024, 89 min) is a harrowing docudrama that makes a powerful appeal to humanity.