### 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)

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"""Variable subcommands."""
from __future__ import annotations
import json
import os
from json import JSONDecodeError
from sqlalchemy import select
from airflow.cli.simple_table import AirflowConsole
from airflow.models import Variable
from airflow.utils import cli as cli_utils
from airflow.utils.cli import suppress_logs_and_warning
from airflow.utils.providers_configuration_loader import providers_configuration_loaded
from airflow.utils.session import create_session
@suppress_logs_and_warning
@providers_configuration_loaded
def variables_list(args):
    """Displays all the variables."""
    with create_session() as session:
        variables = session.scalars(select(Variable)).all()
    AirflowConsole().print_as(data=variables, output=args.output, mapper=lambda x: {"key": x.key})
@suppress_logs_and_warning
@providers_configuration_loaded
def variables_get(args):