**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
num_active_runs.get(dag.dag_id, 0),
            )
            for orm_tag in list(orm_dag.tags):
                if orm_tag.name not in orm_dag.tags:
                    session.delete(orm_tag)
                orm_dag.tags.remove(orm_tag)
            if dag.tags:
                orm_tag_names = [t.name for t in orm_dag.tags]
                for dag_tag in list(dag.tags):
                    if dag_tag not in orm_tag_names:
                        dag_tag_orm = DagTag(name=dag_tag, dag_id=dag.dag_id)
                        orm_dag.tags.append(dag_tag_orm)
                        session.add(dag_tag_orm)
        if settings.STORE_DAG_CODE:
            DagCode.bulk_sync_to_db([dag.fileloc for dag in orm_dags])
        
        
        session.flush()
        for dag in dags:
            cls.bulk_write_to_db(dag.subdags, session=session)
    @provide_session
    def sync_to_db(self, session=None):
        """
        Save attributes about this DAG to the DB. Note that this method
        can be called for both DAGs and SubDAGs. A SubDag is actually a
        SubDagOperator.
        :return: None
        """
        self.bulk_write_to_db([self], session)
    def get_default_view(self):