feat(holiday-system): implement comprehensive holiday management features

- Added holiday types and organization holidays management with CRUD operations.
- Introduced country holidays import functionality using the date-holidays npm package.
- Created database migrations for holiday types and organization holidays tables.
- Developed a holiday calendar component for visual representation and management of holidays.
- Enhanced API routes for holiday-related operations and integrated them into the admin center.
- Updated frontend localization for holiday management features.
- Implemented scripts for populating holidays in the database for 200+ countries.

worklenz-backend/package.json

@@ -61,6 +61,7 @@
     "crypto-js": "^4.1.1",
     "csrf-sync": "^4.2.1",
     "csurf": "^1.11.0",
+    "date-holidays": "^3.24.4",
     "debug": "^4.3.4",
     "dotenv": "^16.3.1",
     "exceljs": "^4.3.0",