### 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.
help="Rotate encrypted connection credentials and variables",
        description=(
            "Rotate all encrypted connection credentials and variables; see "
            "https://airflow.apache.org/docs/apache-airflow/stable/howto/secure-connections.html"
            "#rotating-encryption-keys"
        ),
        args=(),
    ),
    GroupCommand(name="config", help="View configuration", subcommands=CONFIG_COMMANDS),
    ActionCommand(
        name="info",
        help="Show information about current Airflow and environment",
        func=lazy_load_command("airflow.cli.commands.info_command.show_info"),
        args=(
            ARG_ANONYMIZE,
            ARG_FILE_IO,
            ARG_VERBOSE,
            ARG_OUTPUT,
        ),
    ),
    ActionCommand(
        name="plugins",
        help="Dump information about loaded plugins",
        func=lazy_load_command("airflow.cli.commands.plugins_command.dump_plugins"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="standalone",
        help="Run an all-in-one copy of Airflow",
        func=lazy_load_command("airflow.cli.commands.standalone_command.standalone"),