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.

resp = client_single_dag.get(page, follow_redirects=True)
    check_content_in_response("Import Errors", resp)
    
    check_content_in_response(f"/{TEST_FILTER_DAG_IDS[0]}.py", resp)
    
    for dag_id in TEST_FILTER_DAG_IDS[1:]:
        check_content_not_in_response(f"/{dag_id}.py", resp)
def test_home_dag_list(working_dags, user_client):
    
    resp = user_client.get("home", follow_redirects=True)
    for dag_id in TEST_FILTER_DAG_IDS:
        check_content_in_response(f"dag_id={dag_id}", resp)
def test_home_dag_list_filtered_singledag_user(working_dags_with_read_perm, client_single_dag):
    
    resp = client_single_dag.get("home", follow_redirects=True)
    
    check_content_in_response(f"dag_id={TEST_FILTER_DAG_IDS[0]}", resp)
    
    for dag_id in TEST_FILTER_DAG_IDS[1:]:
        check_content_not_in_response(f"dag_id={dag_id}", resp)
def test_home_dag_list_search(working_dags, user_client):
    resp = user_client.get("home?search=filter_test", follow_redirects=True)
    check_content_in_response("dag_id=filter_test_1", resp)
    check_content_in_response("dag_id=filter_test_2", resp)
    check_content_not_in_response("dag_id=filter.test", resp)
    check_content_not_in_response("dag_id=a_first_dag_id_asc", resp)
def test_home_dag_edit_permissions(capture_templates, working_dags_with_edit_perm, client_single_dag_edit):