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/utilities/Validator.cpp

@@ -108,6 +108,17 @@ bool util::isPasswordValid(const std::string& password)
     return hasUpper && hasLower && hasDigit && hasSpecial;
 }
 
+/*
+ * Function: isUsernameDuplicate
+ * Description: Checks if the given username already exists among active users.
+ * Parameters:
+ *     username - string containing the username to validate
+ *     usersMap - map of user objects keyed by identifier
+ * Returns:
+ *     bool - true if the username is already in use by an active user, false otherwise
+ * Notes:
+ *     - Only considers users with state util::State::ACTIVE
+ */
 bool util::isUsernameDuplicate(const std::string& username, const util::Map<std::string, User*>& usersMap)
 {
     int index = usersMap.findIf(
@@ -119,6 +130,17 @@ bool util::isUsernameDuplicate(const std::string& username, const util::Map<std:
     return index != -1;
 }
 
+/*
+ * Function: isPhoneDuplicate
+ * Description: Checks if the given phone number already exists among active users.
+ * Parameters:
+ *     phone - string containing the phone number to validate
+ *     usersMap - map of user objects keyed by identifier
+ * Returns:
+ *     bool - true if the phone number is already in use by an active user, false otherwise
+ * Notes:
+ *     - Only considers users with state util::State::ACTIVE
+ */
 bool util::isPhoneDuplicate(const std::string& phone, const util::Map<std::string, User*>& usersMap)
 {
     int index = usersMap.findIf(
@@ -130,6 +152,17 @@ bool util::isPhoneDuplicate(const std::string& phone, const util::Map<std::strin
     return index != -1;
 }
 
+/*
+ * Function: isEmailDuplicate
+ * Description: Checks if the given email address already exists among active users.
+ * Parameters:
+ *     email - string containing the email address to validate
+ *     usersMap - map of user objects keyed by identifier
+ * Returns:
+ *     bool - true if the email address is already in use by an active user, false otherwise
+ * Notes:
+ *     - Only considers users with state util::State::ACTIVE
+ */
 bool util::isEmailDuplicate(const std::string& email, const util::Map<std::string, User*>& usersMap)
 {
     int index = usersMap.findIf(
@@ -139,4 +172,4 @@ bool util::isEmailDuplicate(const std::string& email, const util::Map<std::strin
         }
     );
     return index != -1;
-}
+}