### 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_POOL,
            ARG_CFG_PATH,
            ARG_LOCAL,
            ARG_RAW,
            ARG_IGNORE_ALL_DEPENDENCIES,
            ARG_IGNORE_DEPENDENCIES,
            ARG_IGNORE_DEPENDS_ON_PAST,
            ARG_DEPENDS_ON_PAST,
            ARG_SHIP_DAG,
            ARG_PICKLE,
            ARG_JOB_ID,
            ARG_INTERACTIVE,
            ARG_SHUT_DOWN_LOGGING,
            ARG_MAP_INDEX,
            ARG_VERBOSE,
            ARG_READ_FROM_DB,
        ),
    ),
    ActionCommand(
        name="test",
        help="Test a task instance",
        description=(
            "Test a task instance. This will run a task without checking for dependencies or recording "
            "its state in the database"
        ),
        func=lazy_load_command("airflow.cli.commands.task_command.task_test"),
        args=(
            ARG_DAG_ID,
            ARG_TASK_ID,
            ARG_EXECUTION_DATE_OR_RUN_ID_OPTIONAL,