The DAGs main page has All/Active/Paused.

It would be nice if we can have also Running Now which will show all the DAGs that have at least 1 in Running of DAG runs:
![Screen Shot 2021-08-25 at 11 30 55](https://user-images.githubusercontent.com/62940116/130756490-647dc664-7528-4eb7-b4d8-515577f7e6bb.png)


For the above example the new DAGs tab of Running Now should show only 2 rows.
The use case is to see easily what DAGs are currently in progress.

for attr_name, attr in (
                (attr_name, getattr(dag_model, attr_name))
                for attr_name in dir(dag_model)
                if not attr_name.startswith("_") and attr_name not in attrs_to_avoid
            )
            if not callable(attr)
        ]
        return self.render_template(
            "airflow/dag_details.html",
            dag=dag,
            dag_model=dag_model,
            title=title,
            root=root,
            states=states,
            State=State,
            active_runs=active_runs,
            tags=tags,
            owner_links=owner_links,
            dag_model_attrs=dag_model_attrs,
        )
    @expose("/rendered-templates")
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_DAG),
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_TASK_INSTANCE),
        ]
    )
    @action_logging
    @provide_session
    def rendered_templates(self, session):