Complete plugin rewrite and updated to work on 1.21+

• Completely rewritten the core flight and fuel logic for better performance
• Added messages.yml for full localization support
• Added support for hex color codes in messages ({#RRGGBB})

IMPORTANT: You must delete your entire old JetpackPlugin folder and config files before running this update. The old configuration format is incompatible and will cause errors!

Let me know if you run into any issues with the new rewrite.