### Description

Recently, we added [a new DAG dependencies view](https://github.com/apache/airflow/pull/13199) to the webserver. It would be helpful if a similar diagram could also be displayed/generated using the CLI. For now, only [one DAG can be displayed](http://airflow.apache.org/docs/apache-airflow/stable/usage-cli.html#exporting-dag-structure-as-an-image) using CLI.
![image](https://user-images.githubusercontent.com/12058428/137945580-6a33f919-2648-4980-bd2c-b40cfcacc9fe.png)

If anyone is interested, I will be happy to help with the review.

### Use case/motivation

* Keep parity between CLI and web serwer.
* Enable the writing of scripts that use these diagrams, e.g. for attaching in the documentation.

### Related issues

https://github.com/apache/airflow/pull/13199/files

### Are you willing to submit a PR?

- [ ] 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)

airflow/cli/cli_parser.py
args=(ARG_POOL_EXPORT,),
    ),
)
VARIABLES_COMMANDS = (
    ActionCommand(
        name='list',
        help='List variables',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_list'),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name='get',
        help='Get variable',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_get'),
        args=(ARG_VAR, ARG_JSON, ARG_DEFAULT, ARG_VERBOSE),
    ),
    ActionCommand(
        name='set',
        help='Set variable',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_set'),
        args=(ARG_VAR, ARG_VAR_VALUE, ARG_JSON),
    ),
    ActionCommand(
        name='delete',
        help='Delete variable',
        func=lazy_load_command('airflow.cli.commands.variable_command.variables_delete'),
        args=(ARG_VAR,),
    ),
    ActionCommand(
        name='import',