Added CSV header support and persistence for employees

<SRS> SRS02 : Employee Management </SRS>

<Changes>
 - Added header handling in FileManager load by skipping first line during deserialization
 - Added support for writing headers using T::getHeaders() in FileManager save
 - Implemented getHeaders() for Employee and GeneralEmployee models
 - Added saveEmployees functionality in EmployeeManagementService
 - Added persistStates method in ZenvyController
 - Added deserialization failure check with exception handling
 - Minor formatting cleanup in FileIO
</Changes>

<Review>
Smitha Mohan
</Review>

Trenser.Zenvy/Trenser.Zenvy/views/UserInterface.cpp

@@ -47,6 +47,15 @@ void UserInterface::run()
 			util::pressEnter();
 		}
 	}
+    try
+    {
+        m_controller->persistStates();
+    }
+    catch (const std::exception& e)
+	{
+	    std::cout << "Exception: " << e.what() << std::endl;
+        return;
+    }
 }
 
 bool UserInterface::handleOperation(int choice)