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.

"Using forward slash ('/') in a DAG run ID is deprecated. Note that this character "
                "also makes the run impossible to retrieve via Airflow's REST API.",
                "warning",
            )
        run_conf = {}
        if request_conf:
            try:
                run_conf = json.loads(request_conf)
                if not isinstance(run_conf, dict):
                    flash("Invalid JSON configuration, must be a dict", "error")
                    form = DateTimeForm(data={"execution_date": execution_date})
                    return self.render_template(
                        "airflow/trigger.html",
                        form_fields=form_fields,
                        dag_id=dag_id,
                        origin=origin,
                        conf=request_conf,
                        form=form,
                        is_dag_run_conf_overrides_params=is_dag_run_conf_overrides_params,
                        recent_confs=recent_confs,
                    )
            except json.decoder.JSONDecodeError:
                flash("Invalid JSON configuration, not parseable", "error")
                form = DateTimeForm(data={"execution_date": execution_date})
                return self.render_template(
                    "airflow/trigger.html",
                    form_fields=form_fields,
                    dag_id=dag_id,
                    origin=origin,
                    conf=request_conf,