### 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)

ActionCommand(
        name="test",
        help="Test a connection",
        func=lazy_load_command("airflow.cli.commands.connection_command.connections_test"),
        args=(ARG_CONN_ID, ARG_VERBOSE),
    ),
    ActionCommand(
        name="create-default-connections",
        help="Creates all the default connections from all the providers",
        func=lazy_load_command("airflow.cli.commands.connection_command.create_default_connections"),
        
        args=(ARG_VERBOSE,),
    ),
)
PROVIDERS_COMMANDS = (
    ActionCommand(
        name="list",
        help="List installed providers",
        func=lazy_load_command("airflow.cli.commands.provider_command.providers_list"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="get",
        help="Get detailed information about a provider",
        func=lazy_load_command("airflow.cli.commands.provider_command.provider_get"),
        args=(ARG_OUTPUT, ARG_VERBOSE, ARG_FULL, ARG_COLOR, ARG_PROVIDER_NAME),
    ),
    ActionCommand(
        name="links",
        help="List extra links registered by the providers",