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.

)
            .filter_by(execution_date=dttm, dag_id=dag_id, task_id=task_id, map_index=map_index)
            .one_or_none()
        )
        if ti is None:
            ti_attrs: list[tuple[str, Any]] | None = None
        else:
            ti.refresh_from_task(task)
            ti_attrs_to_skip = [
                "dag_id",
                "key",
                "mark_success_url",
                "log",
                "log_url",
                "task",
                "trigger",
                "triggerer_job",
            ]
            
            with warnings.catch_warnings():
                warnings.simplefilter("ignore", RemovedInAirflow3Warning)
                all_ti_attrs = (
                    (name, getattr(ti, name))
                    for name in dir(ti)
                    if not name.startswith("_") and name not in ti_attrs_to_skip
                )
            ti_attrs = sorted((name, attr) for name, attr in all_ti_attrs if not callable(attr))
        attr_renderers = wwwutils.get_attr_renderer()
        attrs_to_skip: frozenset[str] = getattr(task, "HIDE_ATTRS_FROM_UI", frozenset())
        def include_task_attrs(attr_name):