Enable TinyMCE Localisation

`app/assets/javascripts/langs/fr_FR.js` was downloaded from https://www.tiny.cloud/get-tiny/language-packages/

Author: aaronskiba

app/assets/javascripts/langs/fr_FR.js

@@ -53,6 +53,7 @@ export const defaultOptions = {
   // is not supported, see issue https://github.com/tinymce/tinymce/issues/358
   skin_url: '/tinymce/skins/oxide',
   content_css: ['/tinymce/tinymce.css'],
+  ...(window.i18nLocale === 'fr-CA' && { language: 'fr_FR' }) // handles language switching for DMP Assistant
 };
 
 /*