### 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)

func=lazy_load_command("airflow.cli.commands.provider_command.extra_links_list"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="widgets",
        help="Get information about registered connection form widgets",
        func=lazy_load_command("airflow.cli.commands.provider_command.connection_form_widget_list"),
        args=(
            ARG_OUTPUT,
            ARG_VERBOSE,
        ),
    ),
    ActionCommand(
        name="hooks",
        help="List registered provider hooks",
        func=lazy_load_command("airflow.cli.commands.provider_command.hooks_list"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="triggers",
        help="List registered provider triggers",
        func=lazy_load_command("airflow.cli.commands.provider_command.triggers_list"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="behaviours",
        help="Get information about registered connection types with custom behaviours",
        func=lazy_load_command("airflow.cli.commands.provider_command.connection_field_behaviours"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),