### 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)

tests/utils/test_dot_renderer.py
with DAG(dag_id="example_task_group", start_date=START_DATE) as dag:
            start = DummyOperator(task_id="start")
            with TaskGroup("section_1", tooltip="Tasks for section_1") as section_1:
                task_1 = DummyOperator(task_id="task_1")
                task_2 = BashOperator(task_id="task_2", bash_command='echo 1')
                task_3 = DummyOperator(task_id="task_3")
                task_1 >> [task_2, task_3]
            with TaskGroup("section_2", tooltip="Tasks for section_2") as section_2:
                task_1 = DummyOperator(task_id="task_1")
                with TaskGroup("inner_section_2", tooltip="Tasks for inner_section2"):
                    task_2 = BashOperator(task_id="task_2", bash_command='echo 1')
                    task_3 = DummyOperator(task_id="task_3")
                    task_4 = DummyOperator(task_id="task_4")
                    [task_2, task_3] >> task_4
            end = DummyOperator(task_id='end')
            start >> section_1 >> section_2 >> end