NewV1Handler is a legacy handler for job status - GET /v1/job-status/{job_run_id} - returns job status - DELETE /v1/job-status/{job_run_id} - deletes job status AND failed records - GET /v1/job-status/{job_run_id}/failed-records - returns failed records TODO: delete this handler once we remove support for the v1 api.

NewFailedKeysHandler creates a handler for failed keys - GET /v2/job-status/{job_run_id} - DELETE /v2/job-status/{job_run_id} - GET /v2/failed-keys/{job_run_id} - DELETE /v2/failed-keys/{job_run_id}.