Upgrade compatibility tool fixes

[00110000]

Description
This pull request resolves runtime errors in the Upgrade Compatibility Tool (UCT):

• ConfigurationDialog
  • Corrected icon path from general/information.png to icons/information.png to prevent java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null.
  • Removed non-existent this.buttonOk and this.buttonCancel references to resolve java.lang.NullPointerException.
  • Added missing init() call to ensure the dialog content is properly initialised and is not displayed as a blank modal window.
• ReindexDialog
  • Removed non-existent this.buttonOk and this.buttonCancel references to resolve java.lang.NullPointerException.
• SupportedVersion
  • Changed from enum to class as the enum no longer had any static values and was relying on realtime calls to Packagist. The UCT tool was erroring when calling SupportedVersion.values() and when trying to get enum 2.3.0 (as a default fallback) because the enum didn't have any values. The entire plugin has been updated to use the new class functions.

Fixed Issues

1. Fixes java.lang.IllegalArgumentException: No enum constant com.magento.idea.magento2uct.packages.SupportedVersion.2.3.0 #2503
2. Fixes Bug Report 2025/04/11 for the upgrade compatibility tool #2515
3. Fixes Bug Report 2025/04/30 #2528
4. Fixes Bug Report 2025/06/04 #2557
5. Fixes Bug Report 2025/07/06 #2573

This also resolves the following issue(s) which have been marked as completed/resolved but are still occurring in the latest version of the plugin:

• Fixes Configure Upgrade Compatibility Tool #2464

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with integration/functional tests (if applicable)
• All automated tests passed successfully (all builds are green)