Enhance employee and user management with linked user functionality

- Introduced `EmployeeUserWrite` type to manage user details associated with employees.
- Updated `EmployeesService` and `EmployeesRepository` to support user assignment and retrieval by user ID.
- Enhanced DTOs to include user information for employee creation and updates.
- Implemented validation to ensure proper handling of user data during employee operations.
- Added unit and e2e tests to validate the new functionality and ensure data integrity in user-employee relationships.
- Modified existing controllers to accommodate the new user linkage features in employee management.

src/modules/configuration/employees/employees-write.controller.spec.ts

@@ -38,6 +38,7 @@ describe('EmployeesWriteController', () => {
       status: undefined,
       userId: 'user-1',
       assignedUserId: undefined,
+      user: undefined,
     });
   });