### 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/cli/commands/test_dag_command.py
dag_command.dag_backfill(
            self.parser.parse_args(
                ['dags', 'backfill', 'example_bash_operator', '--start-date', DEFAULT_DATE.isoformat()]
            )
        )
        mock_run.assert_called_once_with(
            start_date=DEFAULT_DATE,
            end_date=DEFAULT_DATE,
            conf=None,
            delay_on_limit_secs=1.0,
            donot_pickle=False,
            ignore_first_depends_on_past=True,
            ignore_task_deps=False,
            local=False,
            mark_success=False,
            pool=None,
            rerun_failed_tasks=False,
            run_backwards=False,
            verbose=False,
        )
        mock_run.reset_mock()
        dag = self.dagbag.get_dag('example_bash_operator')
        with contextlib.redirect_stdout(io.StringIO()) as stdout:
            dag_command.dag_backfill(
                self.parser.parse_args(
                    [
                        'dags',