add a command to create playlist from folder structure
requested to merge petitminion/funkwhale-petitminion:2223-add-create_playlist_from_folder_structure-command into develop
Closes #2223
docker compose -f dev.yml run --rm api funkwhale-manage create_playlist_from_folder_structure --user_id 1 --dir_name "/data/media/some_test_folder" --privacy_level "everyone"