**Description**

It would be great having a option to abort a DAG Runs through the REST API.

**Use case / motivation**

The proposed input params would be:
 - DAG_ID
 - DAG_RUN_ID

The DAG Run should abort all its tasks running and mark them as "failed".

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

**Related Issues**


airflow/api_connexion/endpoints/dag_run_endpoint.py
#
#
from flask import current_app, g, request
from marshmallow import ValidationError
from sqlalchemy import or_
from airflow._vendor.connexion import NoContent
from airflow.api_connexion import security
from airflow.api_connexion.exceptions import AlreadyExists, BadRequest, NotFound
from airflow.api_connexion.parameters import apply_sorting, check_limit, format_datetime, format_parameters
from airflow.api_connexion.schemas.dag_run_schema import (
    DAGRunCollection,
    dagrun_collection_schema,
    dagrun_schema,
    dagruns_batch_form_schema,
)
from airflow.models import DagModel, DagRun
from airflow.security import permissions
from airflow.utils.session import provide_session
from airflow.utils.state import State
from airflow.utils.types import DagRunType
@security.requires_access(
    [
        (permissions.ACTION_CAN_READ, permissions.RESOURCE_DAG),
        (permissions.ACTION_CAN_DELETE, permissions.RESOURCE_DAG_RUN),
    ]
)
@provide_session
def delete_dag_run(dag_id, dag_run_id, session):