[#337] added timezone loading from backend (#386)

* [#337] added timezone loading from backend

* [#337] changed data structure to allow patching timezone while keeping other datetime params value

* [#337] fixed gap, event create modale sync with settings and added checkbox

* [#337] isBrowserDefaultTimezone is set to true when API return null timezone

Co-authored-by: Camille Moussu <cmoussu@linagora.com>

src/App.tsx

@@ -41,7 +41,9 @@ const isValidLanguage = (
 
 function App() {
   const error = useAppSelector((state) => state.user.error);
-  const userLanguage = useAppSelector((state) => state.user.language);
+  const userLanguage = useAppSelector(
+    (state) => state.user.coreConfig.language
+  );
   const settingsLanguage = useAppSelector((state) => state.settings.language);
   const savedLang = localStorage.getItem("lang");
   const defaultLang = (window as any).LANG;