### 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
dot = dot_renderer.render_dag(dag)
        assert dot.source.strip() == '\n'.join(
            [
                'digraph example_task_group {',
                '\tgraph [label=example_task_group labelloc=t rankdir=LR]',
                '\tend [color="#000000" fillcolor="#e8f7e4" label=end shape=rectangle '
                'style="filled,rounded"]',
                '\tsubgraph cluster_section_1 {',
                '\t\tcolor="#000000" fillcolor="#6495ed7f" label=section_1 shape=rectangle style=filled',
                '\t\t"section_1.upstream_join_id" [color="#000000" fillcolor=CornflowerBlue height=0.2 '
                'label="" shape=circle style="filled,rounded" width=0.2]',
                '\t\t"section_1.downstream_join_id" [color="#000000" fillcolor=CornflowerBlue height=0.2 '
                'label="" shape=circle style="filled,rounded" width=0.2]',
                '\t\t"section_1.task_1" [color="#000000" fillcolor="#e8f7e4" label=task_1 shape=rectangle '
                'style="filled,rounded"]',
                '\t\t"section_1.task_2" [color="#000000" fillcolor="#f0ede4" label=task_2 shape=rectangle '
                'style="filled,rounded"]',
                '\t\t"section_1.task_3" [color="#000000" fillcolor="#e8f7e4" label=task_3 shape=rectangle '
                'style="filled,rounded"]',
                '\t}',
                '\tsubgraph cluster_section_2 {',
                '\t\tcolor="#000000" fillcolor="#6495ed7f" label=section_2 shape=rectangle style=filled',
                '\t\t"section_2.upstream_join_id" [color="#000000" fillcolor=CornflowerBlue height=0.2 '
                'label="" shape=circle style="filled,rounded" width=0.2]',
                '\t\t"section_2.downstream_join_id" [color="#000000" fillcolor=CornflowerBlue height=0.2 '
                'label="" shape=circle style="filled,rounded" width=0.2]',
                '\t\tsubgraph "cluster_section_2.inner_section_2" {',
                '\t\t\tcolor="#000000" fillcolor="#6495ed7f" label=inner_section_2 shape=rectangle '
                'style=filled',
                '\t\t\t"section_2.inner_section_2.task_2" [color="#000000" fillcolor="#f0ede4" label=task_2 '