**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**



tests/api_connexion/endpoints/test_task_instance_endpoint.py
},
            {
                "execution_date": DEFAULT_DATETIME_1 + dt.timedelta(days=4),
                "state": State.RUNNING,
            },
        ]
        self.create_task_instances(
            session,
            dag_id=dag_id,
            single_dag_run=False,
            task_instances=task_instances,
            update_extras=False,
            dag_run_state=State.FAILED,
        )
        response = self.client.post(
            f"/api/v1/dags/{dag_id}/clearTaskInstances",
            environ_overrides={"REMOTE_USER": "test"},
            json=payload,
        )
        failed_dag_runs = (
            session.query(DagRun).filter(DagRun.state == "failed").count()  
        )
        assert 200 == response.status_code
        expected_response = [
            {
                'dag_id': 'example_python_operator',
                'dag_run_id': 'TEST_DAG_RUN_ID_0',
                'execution_date': '2020-01-01T00:00:00+00:00',
                'task_id': 'print_the_context',
            },