chore(i18n): fix UCD extraction for Node 10.x

Previously (e.g. Node.js 8.x), the 3rd argument to `fs.writeFile()`
(i.e. the callback) could be undefined. On Node.js 10.x, this throws an
error.

This commit fixes it by switching to `fs.writeFileSync()` which seems to
have been the original intention (based on the sorrounding code).

i18n/ucd/src/extract.js

@@ -20,7 +20,7 @@ function main() {
     } catch (e) {
       fs.mkdirSync(__dirname + '/../../../src/ngParseExt');
     }
-    fs.writeFile(__dirname + '/../../../src/ngParseExt/ucd.js', code);
+    fs.writeFileSync(__dirname + '/../../../src/ngParseExt/ucd.js', code);
   }
 }