Set up localization with feature flag control (#9649)

Refers #8128 

Changes Introduced:
- Added i18n configuration.
- Added a feature flag for localization.
- Enabled language switching based on the flag.

---------

Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-website/src/content/developers/frontend-development/frontend-commands.mdx

@@ -28,6 +28,13 @@ npx nx run twenty-front:graphql:generate
 npx nx run twenty-front:lint # pass --fix to fix lint errors
 ```
 
+## Translations
+
+```bash
+npx nx run twenty-front:lingui:extract
+npx nx run twenty-front:lingui:compile
+```
+
 ### Test
 
 ```bash