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.

"""View to show records from Variable table."""
    route_base = "/variable"
    list_template = "airflow/variable_list.html"
    edit_template = "airflow/variable_edit.html"
    show_template = "airflow/variable_show.html"
    show_widget = AirflowVariableShowWidget
    datamodel = AirflowModelView.CustomSQLAInterface(models.Variable)  
    class_permission_name = permissions.RESOURCE_VARIABLE
    method_permission_name = {
        "add": "create",
        "list": "read",
        "edit": "edit",
        "show": "read",
        "delete": "delete",
        "action_muldelete": "delete",