Cloud Task callback for creating a single credentialing workflow

Called by Cloud Tasks as part of the v2 bulk-create flow. Creates a single credentialing workflow and updates the bulk request item status. Required body fields: certifyPractitionerId (string), tenantPractitionerId (string), credentialingWorkflowBulkRequestId (string), credentialingWorkflowBulkRequestItemId (string). Optional body field: data (object) - workflow creation payload.