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.

"""Dag Code."""
        dag = get_airflow_app().dag_bag.get_dag(dag_id, session=session)
        dag_model = DagModel.get_dagmodel(dag_id, session=session)
        if not dag or not dag_model:
            flash(f'DAG "{dag_id}" seems to be missing.', "error")
            return redirect(url_for("Airflow.index"))
        wwwutils.check_import_errors(dag_model.fileloc, session)
        wwwutils.check_dag_warnings(dag_model.dag_id, session)
        try:
            code = DagCode.get_code_by_fileloc(dag_model.fileloc)
            html_code = Markup(highlight(code, lexers.PythonLexer(), HtmlFormatter(linenos=True)))
        except Exception as e:
            error = f"Exception encountered during dag code retrieval/code highlighting:\n\n{e}\n"
            html_code = Markup("<p>Failed to load DAG file Code.</p><p>Details: {}</p>").format(escape(error))
        return self.render_template(
            "airflow/dag_code.html",
            html_code=html_code,
            dag=dag,
            dag_model=dag_model,
            title=dag_id,
            root=request.args.get("root"),
            wrapped=conf.getboolean("webserver", "default_wrap"),
        )
    @expose("/dag_details")