### Body

The CLI:

`airflow variables set [-h] [-j] [-v] key VALUE`

https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html#set_repeat1

Doesn't support adding description though column exists and we support it from Rest API:
https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html#operation/post_variables

**The Task:**

Allow to set description from cli command

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
"""Class to keep information about command line argument."""
    def __init__(
        self,
        flags=_UNSET,
        help=_UNSET,
        action=_UNSET,
        default=_UNSET,
        nargs=_UNSET,
        type=_UNSET,
        choices=_UNSET,
        required=_UNSET,
        metavar=_UNSET,
        dest=_UNSET,
    ):
        self.flags = flags
        self.kwargs = {}
        for k, v in locals().items():
            if k not in ("self", "flags") and v is not _UNSET:
                self.kwargs[k] = v
    def add_to_parser(self, parser: argparse.ArgumentParser):