[BE] GET /flow/job/{job_id}/status

[HYChou0515]

response

code 200
{
state: created/processing/finished
start_time: 'YYYY-MM-DD HH:MI:SS' or undefined
finish_time: 'YYYY-MM-DD HH:MI:SS' or undefined
error: undefined or ['error1', 'error2', ...]
result: result in json
}

code 404
job_id not found