“ Adolescence ” breakout Owen Cooper has won the BAFTA TV Award for supporting actor, a win that completes an astonishing full set of major awards for the 16-year-old’s first-ever screen role. The win on Sunday night — aptly on home soil for the fast-rising British star — cements Cooper’s place in TV history, with him already having become the youngest actor to win the four major U.S. TV awards — Primetime Emmy, Golden Globe, Actor Award and Critics Choice — for a single performance. Almost 14 months to the day that “Adolescence” launched, it has scooped up a near-perfect clean sweep of wins, also including at the Gotham Awards, Independent Spirit Awards, Royal Television Society Awards, its astonishing awards run has now been completed at the BAFTAs. Popular on Variety “Wow , it’s heavy that to be fair,” Cooper said as he lifted the award. “A year ago this time last year I was presenting an award and now I’m collecting one, so this is a bit mad.” “Thank you to BAFTA.…