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-server/src/database/typeorm-seeds/core/feature-flags.ts

@@ -75,6 +75,11 @@ export const seedFeatureFlags = async (
         workspaceId: workspaceId,
         value: true,
       },
+      {
+        key: FeatureFlagKey.IsLocalizationEnabled,
+        workspaceId: workspaceId,
+        value: true,
+      },
     ])
     .execute();
 };