### Body

There are some use cases where users want to trigger new DAG run as soon as one finished. This is a request I've seen several times with some variations (for example like this [Stackoverflow question](https://stackoverflow.com/q/75623153/14624409)) but the basic request is the same.

The workaround users do to get such functionality is place `TriggerDagRunOperator` as last task of their DAG invoking the same DAG:

```
from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule=None,
) as dag:
    task = EmptyOperator(task_id="first")
    trigger = TriggerDagRunOperator(
        task_id="trigger",
        trigger_dag_id="example",
    )

    task >> trigger

```

As you can see this works nicely:
![Screenshot 2023-03-03 at 14 20 51](https://user-images.githubusercontent.com/45845474/222718862-dfde8a41-24b6-4991-b318-b7f9784514f6.png)

My suggestion is to add first class support for this use case, so the above example will be changed to:

```

from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule="@continues",
) as dag:
    task = EmptyOperator(task_id="first")
```

I guess it won't exactly be `"@continues"` but more likely new [ScheduleArg](https://github.com/apache/airflow/blob/8b8552f5c4111fe0732067d7af06aa5285498a79/airflow/models/dag.py#L127) type but I show it like that just for simplification of the idea.

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
child_dag = DAG(
            "parent_dag.child_dag",
            schedule="@daily",
            start_date=DEFAULT_DATE,
        )
        with child_dag:
            EmptyOperator(task_id="a_child")
            EmptyOperator(task_id="b_child")
        parent_dag = DAG(
            "parent_dag",
            schedule="@daily",
            start_date=DEFAULT_DATE,
        )
        
        with parent_dag:
            op1 = EmptyOperator(task_id="a_parent")
            op2 = SubDagOperator(task_id="child_dag", subdag=child_dag)
            op3 = EmptyOperator(task_id="b_parent")
            op1 >> op2 >> op3
        topological_list = parent_dag.topological_sort(include_subdag_tasks=True)
        assert self._occur_before("a_parent", "child_dag", topological_list)
        assert self._occur_before("child_dag", "a_child", topological_list)
        assert self._occur_before("child_dag", "b_child", topological_list)
        assert self._occur_before("a_child", "b_parent", topological_list)
        assert self._occur_before("b_child", "b_parent", topological_list)
    def test_dag_topological_sort_dag_without_tasks(self):
        dag = DAG("dag", start_date=DEFAULT_DATE, default_args={"owner": "owner1"})
        assert () == dag.topological_sort()
    def test_dag_naive_start_date_string(self):