fix(client): translate navigation warnings (#51026)

client/i18n/locales/english/translations.json

@@ -544,7 +544,8 @@
     "iframe-alert": "Normally this link would bring you to another website! It works. This is a link to: {{externalLink}}",
     "iframe-form-submit-alert": "Normally this form would be submitted! It works. This will be submitted to: {{externalLink}}",
     "document-notfound": "document not found",
-    "slow-load-msg": "Looks like this is taking longer than usual, please try refreshing the page."
+    "slow-load-msg": "Looks like this is taking longer than usual, please try refreshing the page.",
+    "navigation-warning": "If you leave this page, you will lose your progress. Are you sure?"
   },
   "icons": {
     "gold-cup": "Gold Cup",

client/src/templates/Challenges/exam/show.tsx

@@ -348,13 +348,13 @@ class ShowExam extends Component<ShowExamProps, ShowExamState> {
 
   stopWindowClose = (event: Event) => {
     event.preventDefault();
-    alert('stop!');
+    alert(this.props.t('misc.navigation-warning'));
   };
 
   stopBrowserBack = (event: Event) => {
     event.preventDefault();
     window.history.forward();
-    alert('stop!');
+    alert(this.props.t('misc.navigation-warning'));
   };
 
   runExam = () => {