### 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.
run_type = inferred_run_type
            elif run_type == DagRunType.MANUAL and inferred_run_type != DagRunType.MANUAL:
                
                raise ValueError(
                    f"A {run_type.value} DAG run cannot use ID {run_id!r} since it "
                    f"is reserved for {inferred_run_type.value} runs"
                )
        elif run_type and logical_date is not None:  
            run_id = self.timetable.generate_run_id(
                run_type=run_type, logical_date=logical_date, data_interval=data_interval
            )
        else:
            raise AirflowException(
                "Creating DagRun needs either `run_id` or both `run_type` and `execution_date`"
            )
        if run_id and "/" in run_id:
            warnings.warn(
                "Using forward slash ('/') in a DAG run ID is deprecated. Note that this character "
                "also makes the run impossible to retrieve via Airflow's REST API.",
                RemovedInAirflow3Warning,
                stacklevel=3,
            )
        
        copied_params = copy.deepcopy(self.params)
        copied_params.update(conf or {})
        copied_params.validate()
        run = DagRun(
            dag_id=self.dag_id,
            run_id=run_id,