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.

"""Retrieve logs including metadata."""
        dag_id = request.args.get("dag_id")
        task_id = request.args.get("task_id")
        execution_date_str = request.args["execution_date"]
        map_index = request.args.get("map_index", -1, type=int)
        try_number = request.args.get("try_number", type=int)
        metadata_str = request.args.get("metadata", "{}")
        response_format = request.args.get("format", "json")
        
        try:
            metadata: dict = json.loads(metadata_str) or {}
        except json.decoder.JSONDecodeError:
            return {"error": "Invalid JSON metadata"}, 400
        
        try:
            execution_date = timezone.parse(execution_date_str)
        except ValueError:
            error_message = (
                f"Given execution date, {execution_date}, could not be identified as a date. "