### 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
},
            }
        )
    if task_group.downstream_group_ids or task_group.downstream_task_ids:
        
        children.append(
            {
                'id': task_group.downstream_join_id,
                'value': {
                    'label': '',
                    'labelStyle': f"fill:{task_group.ui_fgcolor};",
                    'style': f"fill:{task_group.ui_color};",
                    'shape': 'circle',
                },
            }
        )
    return {
        "id": task_group.group_id,
        'value': {
            'label': task_group.label,
            'labelStyle': f"fill:{task_group.ui_fgcolor};",
            'style': f"fill:{task_group.ui_color}",
            'rx': 5,
            'ry': 5,
            'clusterLabelPos': 'top',
            'tooltip': task_group.tooltip,
        },
        'children': children,
    }
def get_key_paths(input_dict):