### 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)

"""Creates new variable with a given name and value."""
    Variable.set(args.key, args.value, serialize_json=args.json)
    print(f"Variable {args.key} created")
@cli_utils.action_cli
@providers_configuration_loaded
def variables_delete(args):
    """Deletes variable by a given name."""
    Variable.delete(args.key)
    print(f"Variable {args.key} deleted")
@cli_utils.action_cli
@providers_configuration_loaded
def variables_import(args):
    """Imports variables from a given file."""
    if os.path.exists(args.file):
        _import_helper(args.file)
    else:
        raise SystemExit("Missing variables file.")
@providers_configuration_loaded
def variables_export(args):