### Description

In Airflow UI. If we go to Browse --> DAG Runs, then DAG Runs view will be displayed.

Table contains a lot of insightful values likes DAG execution date, Start date, end date, Dag config etc

Request to add DAG duration column in the same table.
DAG Duration i.e. DAG end_date timestamp  - DAG start_date timestamp

### Use case/motivation

Analytics purpose of knowing DAG duration at all DAGs level. So that I can easily find out which DAG  have least and max duration.

### Related issues

Checked open issues. There aren't any

### 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/www/views.py
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import collections
import copy
import json
import logging
import math
import re
import socket
import sys
import traceback
from collections import defaultdict
from datetime import timedelta
from functools import wraps
from json import JSONDecodeError
from operator import itemgetter
from typing import Any, Callable, List, Optional, Set, Tuple, Union
from urllib.parse import parse_qsl, unquote, urlencode, urlparse
import lazy_object_proxy
import markupsafe
import nvd3
import sqlalchemy as sqla