Add logged out translations (#9983)

Add translation for logged in / sub pages

packages/twenty-shared/src/utils/isValidLocale.ts

@@ -0,0 +1,5 @@
+import { APP_LOCALES } from 'src/constants/Locales';
+
+export const isValidLocale = (
+  value: string | null,
+): value is keyof typeof APP_LOCALES => value !== null && value in APP_LOCALES;