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.

def rendered_k8s(self, *, session: Session = NEW_SESSION):
        """Get rendered k8s yaml."""
        if not settings.IS_K8S_OR_K8SCELERY_EXECUTOR:
            abort(404)
        dag_id = request.args.get("dag_id")
        task_id = request.args.get("task_id")
        if task_id is None:
            logging.warning("Task id not passed in the request")
            abort(400)
        execution_date = request.args.get("execution_date")
        dttm = _safe_parse_datetime(execution_date)
        form = DateTimeForm(data={"execution_date": dttm})
        root = request.args.get("root", "")
        map_index = request.args.get("map_index", -1, type=int)
        logging.info("Retrieving rendered templates.")
        dag: DAG = get_airflow_app().dag_bag.get_dag(dag_id)
        task = dag.get_task(task_id)
        dag_run = dag.get_dagrun(execution_date=dttm, session=session)
        ti = dag_run.get_task_instance(task_id=task.task_id, map_index=map_index, session=session)
        pod_spec = None
        try:
            pod_spec = ti.get_rendered_k8s_spec(session=session)
        except AirflowException as e:
            msg = "Error rendering Kubernetes POD Spec: " + escape(e)
            if e.__cause__:
                msg += Markup("<br><br>OriginalError: ") + escape(e.__cause__)
            flash(msg, "error")
        except Exception as e:
            flash("Error rendering Kubernetes Pod Spec: " + str(e), "error")
        title = "Rendered K8s Pod Spec"