Middleware overhaul! (#18218)

* Middleware overhaul!

- Remove unnecessary 'async' keywords from middleware functions
- Ensure all middleware functions we create have names
- Wrap the method contents of all async middleware functions in a try-catch+next(error) pattern

* Use asyncMiddleware wrapper instead of try-catch+next(error) pattern

* Remove unnecessary try-catch+next(error) pattern from context middleware

middleware/detect-language.js

@@ -1,7 +1,7 @@
 const languageCodes = Object.keys(require('../lib/languages'))
 
 // determine language code from first part of URL, or default to English
-module.exports = async function detectLanguage (req, res, next) {
+module.exports = function detectLanguage (req, res, next) {
   // /en/articles/foo
   //  ^^
   const firstPartOfPath = req.path.split('/')[1]