feat: restrict translation to audited certs

utils/is-audited.js

@@ -0,0 +1,15 @@
+// this can go once all certs have been audited.
+function isAuditedCert(lang, cert) {
+  if (!lang || !cert)
+    throw Error('Both arguments must be provided for auditing');
+  // in order to see the challenges in the client, add the certification that
+  // contains those challenges to this array:
+  const auditedCerts = [
+    'responsive-web-design',
+    'javascript-algorithms-and-data-structures',
+    'certificates'
+  ];
+  return lang === 'english' || auditedCerts.includes(cert);
+}
+
+exports.isAuditedCert = isAuditedCert;