Fix Update Profile and User Validation Issues

- Included Validator.h in UserManagementService.cpp for duplicate checks.
- Enhanced updateUserDetails in UserManagementService to validate:
  - Throw error if user does not exist.
  - Throw error if email already exists among active users.
  - Throw error if phone number already exists among active users.
- Implemented new duplicate validation functions in Validator.cpp:
  - isUsernameDuplicate
  - isPhoneDuplicate
  - isEmailDuplicate
- Declared new duplicate validation functions in Validator.h.
- Updated CustomerMenu::updateDetails:
  - Added "Update Details" header for clarity.
  - Improved error messages with newline formatting.
  - Added success message with newline formatting.

Fixes #1746

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/CustomerMenu.cpp

@@ -143,12 +143,14 @@ Return type: void
 void CustomerMenu::updateDetails()
 {
 	std::string email, phone;
+    util::Map<std::string, const User*> userList = m_controller.getUsers();
 	util::clear();
+    std::cout << "Update Details\n";
 	std::cout << "Enter new email: ";
 	util::read(email);
 	if (!util::isEmailValid(email))
 	{
-		std::cout << "Error: Email is invalid!";
+		std::cout << "Error: Email is invalid!\n";
 		util::pressEnter();
 		return;
 	}
@@ -156,12 +158,12 @@ void CustomerMenu::updateDetails()
 	util::read(phone);
 	if (!util::isPhoneNumberValid(phone))
 	{
-		std::cout << "Error: Phone number is invalid!";
+		std::cout << "Error: Phone number is invalid!\n";
 		util::pressEnter();
 		return;
 	}
 	m_controller.updateUserDetails(email, phone);
-	std::cout << "Profile details updated successfully";
+	std::cout << "Profile details updated successfully\n";
 	util::pressEnter();
 }