async function loadMetadataTemplate() {
  const baseName = path.basename(METADATA_TEMPLATE_URL);
  const zipDownloadDest = path.join(os.tmpdir(), baseName);
  await maybeDownload(METADATA_TEMPLATE_URL, zipDownloadDest);

  const zipExtractDir =
      zipDownloadDest.slice(0, zipDownloadDest.length - ZIP_SUFFIX.length);
  await maybeExtract(zipDownloadDest, zipExtractDir);

  return JSON.parse(fs.readFileSync(
      path.join(zipExtractDir,
                baseName.slice(0, baseName.length - ZIP_SUFFIX.length))));
}
Load a metadata template by downloading and extracting files if necessary.

@return A JSON object that is the metadata template.