### 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.
("--treat-dag-as-regex",),
    help=("if set, dag_id will be treated as regex instead of an exact string"),
    action="store_true",
)
ARG_SHOW_DAGRUN = Arg(
    ("--show-dagrun",),
    help=(
        "After completing the backfill, shows the diagram for current DAG Run.\n"
        "\n"
        "The diagram is in DOT language\n"
    ),
    action="store_true",
)
ARG_IMGCAT_DAGRUN = Arg(
    ("--imgcat-dagrun",),
    help=(
        "After completing the dag run, prints a diagram on the screen for the "
        "current DAG Run using the imgcat tool.\n"
    ),
    action="store_true",
)
ARG_SAVE_DAGRUN = Arg(
    ("--save-dagrun",),
    help="After completing the backfill, saves the diagram for current DAG Run to the indicated file.\n\n",
)
ARG_TREE = Arg(("-t", "--tree"), help="Tree view", action="store_true")
ARG_SHUT_DOWN_LOGGING = Arg(
    ("--no-shut-down-logging",),
    help=argparse.SUPPRESS,
    dest="shut_down_logging",