Add argument of channel binning for optical pointing

[TatsumiISHIKAWA]

Description

• In optical pointing script, the argument of channel binning is not enough.

To Reproduce

if __name__ == "__main__":
    description = "Optical Pointing Observation"
    p = argparse.ArgumentParser(description=description)
    p.add_argument(
        "-f",
        "--file",
        type=str,
        help="Path to pointing target file",
        required=True,
    )
    p.add_argument(
        "-l",
        "--lower_mag",
        type=float,
        help="The lower (brightest) limit of target magnitude. e.g. 1.0",
        required=True,
    )
    p.add_argument(
        "-u",
        "--upper_mag",
        type=float,
        help="The upper (darkest) limit of target magnitude. e.g. 3.0",
        required=True,
    )
    p.add_argument(
        "-d",
        "--drive_test",
        type=bool,
        default=False,
        help="If ``True``, execute only driving test (without capturing).",
        required=False,
    )
    p.add_argument(
        "-t",
        "--time",
        type=str,
        help=(
            "Observation time (if inputted, system quits without driving). "
            "e.g. 2023-12-01 09:00:00"
        ),
        required=False,
    )
    p.add_argument(
        "-c",
        "--channel",
        type=int,
        help="Number of spectral channels.",
    )
    args = p.parse_args()

• Note: Optical Pointing observation don't need spectrometer data.