### 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
ARG_RUN_BACKWARDS = Arg(
    (
        "-B",
        "--run-backwards",
    ),
    help=(
        "if set, the backfill will run tasks from the most "
        "recent day first.  if there are tasks that depend_on_past "
        "this option will throw an exception"
    ),
    action="store_true",
)
ARG_SHOW_DAGRUN = Arg(
    ("--show-dagrun",),
    help=(
        "After completing the backfill, shows the diagram for current DAG Run.\n"
        "\n"
        "The diagram is in DOT language\n"
    ),
    action='store_true',
)
ARG_IMGCAT_DAGRUN = Arg(
    ("--imgcat-dagrun",),
    help=(
        "After completing the dag run, prints a diagram on the screen for the "
        "current DAG Run using the imgcat tool.\n"
    ),
    action='store_true',
)
ARG_SAVE_DAGRUN = Arg(