feat: i18n user interface (#40306)

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>

client/i18n/config.js

@@ -0,0 +1,32 @@
+import i18n from 'i18next';
+import { initReactI18next } from 'react-i18next';
+
+const { environment, clientLocale } = require('../config/env');
+const { i18nextCodes } = require('./allLangs');
+
+const i18nextCode = i18nextCodes[clientLocale];
+
+i18n.use(initReactI18next).init({
+  fallbackLng: i18nextCode,
+  lng: i18nextCode,
+  // we only load one language since each language will have it's own server
+  resources: {
+    [i18nextCode]: {
+      translations: require(`./locales/${clientLocale}/translations.json`)
+    }
+  },
+  ns: ['translations'],
+  defaultNS: 'translations',
+  returnObjects: true,
+  debug: environment === 'development',
+  interpolation: {
+    escapeValue: false
+  },
+  react: {
+    wait: true
+  }
+});
+
+i18n.languages = clientLocale;
+
+export default i18n;