### 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)

ARG_PASSWORD,
            ARG_USE_RANDOM_PASSWORD,
            ARG_VERBOSE,
        ),
        epilog=(
            "examples:\n"
            'To create an user with "Admin" role and username equals to "admin", run:\n'
            "\n"
            "    $ airflow users create \\\n"
            "          --username admin \\\n"
            "          --firstname FIRST_NAME \\\n"
            "          --lastname LAST_NAME \\\n"
            "          --role Admin \\\n"
            "          --email admin@example.org"
        ),
    ),
    ActionCommand(
        name="delete",
        help="Delete a user",
        func=lazy_load_command("airflow.cli.commands.user_command.users_delete"),
        args=(ARG_USERNAME_OPTIONAL, ARG_EMAIL_OPTIONAL, ARG_VERBOSE),
    ),
    ActionCommand(
        name="add-role",
        help="Add role to a user",
        func=lazy_load_command("airflow.cli.commands.user_command.add_role"),
        args=(ARG_USERNAME_OPTIONAL, ARG_EMAIL_OPTIONAL, ARG_ROLE, ARG_VERBOSE),
    ),
    ActionCommand(
        name="remove-role",