**Description**

I have noticed that the stable REST API doesn't have the ability to run a task (which is possible from the airflow web interface.
I think it would be nice to have either:
- Run task 
- Run all failing tasks (rerun from point of failure)
this ability for integrations.

**Use case / motivation**

I would like the ability to identify the failing tasks on a specific DAG Run and rerun only them.
I would like to do it remotely (non-interactive) using the REST API.
I could write a script that run only the failing tasks, but I couldn't find a way to "Run" a task, when I have the task instance ID.

**Are you willing to submit a PR?**

Not at this stage

**Related Issues**



airflow/models/dag.py
return settings.ALLOW_FUTURE_EXEC_DATES and self.schedule_interval is None
    @provide_session
    def get_concurrency_reached(self, session=None) -> bool:
        """
        Returns a boolean indicating whether the concurrency limit for this DAG
        has been reached
        """
        TI = TaskInstance
        qry = session.query(func.count(TI.task_id)).filter(
            TI.dag_id == self.dag_id,
            TI.state == State.RUNNING,
        )
        return qry.scalar() >= self.concurrency
    @property
    def concurrency_reached(self):
        """This attribute is deprecated. Please use `airflow.models.DAG.get_concurrency_reached` method."""
        warnings.warn(
            "This attribute is deprecated. Please use `airflow.models.DAG.get_concurrency_reached` method.",
            DeprecationWarning,
            stacklevel=2,
        )
        return self.get_concurrency_reached()
    @provide_session
    def get_is_paused(self, session=None) -> Optional[None]: