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.

clear_db_dags()
    clear_db_import_errors()
    clear_db_serialized_dags()
@pytest.fixture(autouse=True)
def setup():
    clean_db()
    yield
    clean_db()
def test_home(capture_templates, admin_client):
    with capture_templates() as templates:
        resp = admin_client.get("home", follow_redirects=True)
        check_content_in_response("DAGs", resp)
        val_state_color_mapping = (
            "const STATE_COLOR = {"
            '"deferred": "mediumpurple", "failed": "red", '
            '"null": "lightblue", "queued": "gray", '
            '"removed": "lightgrey", "restarting": "violet", "running": "lime", '
            '"scheduled": "tan", '
            '"shutdown": "blue", "skipped": "hotpink", '
            '"success": "green", "up_for_reschedule": "turquoise", '
            '"up_for_retry": "gold", "upstream_failed": "orange"};'
        )
        check_content_in_response(val_state_color_mapping, resp)
    assert len(templates) == 1
    assert templates[0].name == "airflow/dags.html"
    state_color_mapping = State.state_color.copy()
    state_color_mapping["null"] = state_color_mapping.pop(None)
    assert templates[0].local_context["state_color"] == state_color_mapping
def test_home_status_filter_cookie(admin_client):