Six films to watch this week

‘Avatar: Fire and Ash’ gives the franchise a flashy third outing; ‘The Six Billion Dollar Man’ chronicles Julian Assange’s time in Ecuador’s embassy and in prison; ‘Bowie: The Final Act’ is a documentary about the star’s last decades; Kate Winslet’s directing debut ‘Goodbye June’ stars Helen Mirren; Jafar Panahi’s Cannes-winning ‘It Was Just an Accident’ is an illegally filmed Iranian drama; period farce ‘Fackham Hall’ pokes fun at stately home sagas — reviews by Danny Leigh and Jonathan Romney