### 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_SUBDIR,
            ARG_UPSTREAM,
            ARG_DOWNSTREAM,
            ARG_YES,
            ARG_ONLY_FAILED,
            ARG_ONLY_RUNNING,
            ARG_EXCLUDE_SUBDAGS,
            ARG_EXCLUDE_PARENTDAG,
            ARG_DAG_REGEX,
            ARG_VERBOSE,
        ),
    ),
    ActionCommand(
        name="state",
        help="Get the status of a task instance",
        func=lazy_load_command("airflow.cli.commands.task_command.task_state"),
        args=(
            ARG_DAG_ID,
            ARG_TASK_ID,
            ARG_EXECUTION_DATE_OR_RUN_ID,
            ARG_SUBDIR,
            ARG_VERBOSE,
            ARG_MAP_INDEX,
        ),
    ),
    ActionCommand(
        name="failed-deps",
        help="Returns the unmet dependencies for a task instance",
        description=(
            "Returns the unmet dependencies for a task instance from the perspective of the scheduler. "