**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
"""
        Calculates the previous schedule for this dag in UTC
        :param dttm: utc datetime
        :return: utc datetime
        """
        if isinstance(self.normalized_schedule_interval, str):
            
            
            dttm = pendulum.instance(dttm)
            naive = timezone.make_naive(dttm, self.timezone)
            cron = croniter(self.normalized_schedule_interval, naive)
            
            if not self.is_fixed_time_schedule():
                
                delta = naive - cron.get_prev(datetime)
                previous = dttm.in_timezone(self.timezone) - delta
            else:
                
                naive = cron.get_prev(datetime)
                tz = pendulum.timezone(self.timezone.name)
                previous = timezone.make_aware(naive, tz)
            return timezone.convert_to_utc(previous)
        elif self.normalized_schedule_interval is not None:
            return timezone.convert_to_utc(dttm - self.normalized_schedule_interval)
    def next_dagrun_info(