### Description

Currently, the `airflow variables export` command requires an explicit file path and does not support output to stdout. However connections can be printed to stdout using `airflow connections export -`. This inconsistency between the two export commands can lead to confusion and limits the flexibility of the variables export command.

### Use case/motivation

To bring some consistency, similar to connections, variables should also be printed to STDOUT, using `-` instead of filename. 

### Related issues

_No response_

### Are you willing to submit a PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

#
#
"""Connection sub-commands."""
from __future__ import annotations
import io
import json
import os
import sys
import warnings
from pathlib import Path
from typing import Any
from urllib.parse import urlsplit, urlunsplit
from sqlalchemy import select
from sqlalchemy.orm import exc
from airflow.cli.simple_table import AirflowConsole
from airflow.compat.functools import cache
from airflow.configuration import conf
from airflow.exceptions import AirflowNotFoundException
from airflow.hooks.base import BaseHook
from airflow.models import Connection
from airflow.providers_manager import ProvidersManager
from airflow.secrets.local_filesystem import load_connections_dict
from airflow.utils import cli as cli_utils, helpers, yaml
from airflow.utils.cli import suppress_logs_and_warning
from airflow.utils.db import create_default_connections as db_create_default_connections
from airflow.utils.providers_configuration_loader import providers_configuration_loaded
from airflow.utils.session import create_session
def _connection_mapper(conn: Connection) -> dict[str, Any]: