Persist language selection to localStorage

ui/src/App.js

@@ -21,7 +21,7 @@ import createAdminStore from './store/createAdminStore'
 
 const i18nProvider = polyglotI18nProvider(
   (locale) => (messages[locale] ? messages[locale] : messages.en),
-  resolveBrowserLocale()
+  localStorage.getItem('locale') || resolveBrowserLocale()
 )
 
 const history = createHashHistory()

ui/src/personal/Personal.js

@@ -34,6 +34,7 @@ const SelectLanguage = (props) => {
       choices={langChoices}
       onChange={(event) => {
         setLocale(event.target.value)
+        localStorage.setItem('locale', event.target.value)
       }}
     />
   )