John Hiatt, left, and Jerry Douglas are shown making an album together in “Leftover Feelings: A Studio B Revival.” As its title captures perfectly, “Leftover Feelings: A Studio B Revival” — which will be shown by the 2022 Summer New Jersey International Film Festival, June 11 — is two things at once. Leftover Feelings is the title of an excellent 2021 album that teamed singer-songwriter-guitarist John Hiatt with dobro master Jerry Douglas and Douglas’ band. RCA Studio B is where Leftover Feelings was recorded: The Nashville studio was the site of sessions where Elvis Presley, The Everly Brothe…