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.

if get_airflow_app().appbuilder.sm.has_all_dags_access(g.user):
            return query
        filter_dag_ids = get_airflow_app().appbuilder.sm.get_accessible_dag_ids(g.user)
        return query.filter(self.model.dag_id.in_(filter_dag_ids))
class AirflowModelView(ModelView):
    """Airflow Mode View.
    Overridden `__getattribute__` to wraps REST methods with action_logger
    """
    list_widget = AirflowModelListWidget
    page_size = PAGE_SIZE
    CustomSQLAInterface = wwwutils.CustomSQLAInterface
    def __getattribute__(self, attr):
        """Wraps action REST methods with `action_logging` wrapper
        Overriding enables differentiating resource and generation of event name at the decorator level.
        if attr in ["show", "list", "read", "get", "get_list"]:
            return action_logging(event="RESOURCE_NAME"."action_name")(attr)
        else:
            return attr
        """
        attribute = object.__getattribute__(self, attr)
        if (
            callable(attribute)
            and hasattr(attribute, "_permission_name")
            and attribute._permission_name in self.method_permission_name
        ):
            permission_str = self.method_permission_name[attribute._permission_name]
            if permission_str not in ["show", "list", "read", "get", "get_list"]:
                return action_logging(event=f"{self.route_base.strip('/')}.{permission_str}")(attribute)
        return attribute
class AirflowPrivilegeVerifierModelView(AirflowModelView):