### 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.
"revision."
        ),
        func=lazy_load_command("airflow.cli.commands.db_command.downgrade"),
        args=(
            ARG_DB_REVISION__DOWNGRADE,
            ARG_DB_VERSION__DOWNGRADE,
            ARG_DB_SQL_ONLY,
            ARG_YES,
            ARG_DB_FROM_REVISION,
            ARG_DB_FROM_VERSION,
            ARG_VERBOSE,
        ),
    ),
    ActionCommand(
        name="shell",
        help="Runs a shell to access the database",
        func=lazy_load_command("airflow.cli.commands.db_command.shell"),
        args=(ARG_VERBOSE,),
    ),
    ActionCommand(
        name="check",
        help="Check if the database can be reached",
        func=lazy_load_command("airflow.cli.commands.db_command.check"),
        args=(ARG_VERBOSE, ARG_DB_RETRY, ARG_DB_RETRY_DELAY),
    ),
    ActionCommand(
        name="clean",
        help="Purge old records in metastore tables",
        func=lazy_load_command("airflow.cli.commands.db_command.cleanup_tables"),
        args=(