async function getDownloadLink (files, gatewayUrl, ipfs) {
  if (files.length === 1) {
    return getDownloadURL(files[0].type, files[0].name, files[0].cid, gatewayUrl)
  }

  const cid = await makeCIDFromFiles(files, ipfs)
  return getDownloadURL('directory', '', cid, gatewayUrl)
}
@param {FileStat[]} files
@param {string} gatewayUrl
@param {IPFSService} ipfs
@returns {Promise<string>}