code: function getPrivateKeyDetailsFromDriveFile(driveFileId) {
    var file = DriveApp.getFileById(driveFileId);
    return JSON.parse(file.getAs('application/json').getDataAsString());
  }
docs: Parse the private key details from a file stored in Google Drive.
  @param {string} driveFileId The id of the file in drive to parse.