### 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
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import contextlib
import io
import os
import tempfile
import unittest
from datetime import datetime, timedelta
from unittest import mock
from unittest.mock import MagicMock
import pytest
from airflow import settings
from airflow.cli import cli_parser
from airflow.cli.commands import dag_command
from airflow.exceptions import AirflowException
from airflow.models import DagBag, DagModel, DagRun
from airflow.models.serialized_dag import SerializedDagModel
from airflow.utils import timezone
from airflow.utils.session import create_session
from airflow.utils.state import State
from airflow.utils.types import DagRunType
from tests.test_utils.config import conf_vars
from tests.test_utils.db import clear_db_dags, clear_db_runs
dag_folder_path = '/'.join(os.path.realpath(__file__).split('/')[:-1])
DEFAULT_DATE = timezone.make_aware(datetime(2015, 1, 1), timezone=timezone.utc)
TEST_DAG_FOLDER = os.path.join(os.path.dirname(dag_folder_path), 'dags')
TEST_DAG_ID = 'unit_tests'
EXAMPLE_DAGS_FOLDER = os.path.join(
    os.path.dirname(os.path.dirname(os.path.dirname(os.path.realpath(__file__)))), "airflow/example_dags"