User specified output directory in CLI

[harveydevereux]

Could you support a user selected output directory in gracemaker

Currently it must be ./seed/[number]

Something like this would suffice

def get_output_dir(stem: Path, seed: int = 42) -> Path:
    """
    Generate name and make folder
    :param stem:
    :param seed:
    :return:  folder name
    """
    return stem / "seed" / f"{seed}"

alongwith a new CLI argument

    parser.add_argument(
        "output",
        help="output path",
        nargs="?",
        type=Path,
        default=Path.cwd(),
    )