### 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.
elif not task.start_date:
            task.start_date = self.start_date
        
        
        elif self.start_date:
            task.start_date = max(task.start_date, self.start_date)
        
        if not task.end_date:
            task.end_date = self.end_date
        
        
        elif task.end_date and self.end_date:
            task.end_date = min(task.end_date, self.end_date)
        task_id = task.task_id
        if not task.task_group:
            task_group = TaskGroupContext.get_current_task_group(self)
            if task_group:
                task_id = task_group.child_id(task_id)
                task_group.add(task)
        if (
            task_id in self.task_dict and self.task_dict[task_id] is not task
        ) or task_id in self._task_group.used_group_ids:
            raise DuplicateTaskIdFound(f"Task id '{task_id}' has already been added to the DAG")
        else:
            self.task_dict[task_id] = task
            task.dag = self
            
            self._task_group.used_group_ids.add(task_id)
        self.task_count = len(self.task_dict)
    def add_tasks(self, tasks: Iterable[Operator]) -> None: