**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/schemas/dag_run_schema.py
#
#
#
import json
from typing import List, NamedTuple
from marshmallow import fields, post_dump, pre_load
from marshmallow.schema import Schema
from marshmallow.validate import Range
from marshmallow_sqlalchemy import SQLAlchemySchema, auto_field
from pendulum.parsing import ParserError
from airflow.api_connexion.exceptions import BadRequest
from airflow.api_connexion.parameters import validate_istimezone
from airflow.api_connexion.schemas.enum_schemas import DagStateField
from airflow.models.dagrun import DagRun
from airflow.utils import timezone
from airflow.utils.types import DagRunType
class ConfObject(fields.Field):