Tom Blyth: ‘The Hunger Games taught me that I don’t act to get attention’

One of Britain’s most in-demand young actors, the star of ‘The Ballad of Songbirds & Snakes’ speaks to Ellie Muir about his daring new thriller ‘Plainclothes’, his pride over his one-time co-star Rachel Zegler, and how his adult life was shaped by the death of his father