Firewall: NAT: PortForward/Outbound - Refactor to MVC

[preethijacobjt]

This pull request refactors the legacy code for the PortForward and Outbound functionalities in the NAT (Network Address Translation) section of the OPNsense firewall to follow the MVC (Model-View-Controller) design pattern.

Changes:

• Migrated the PortForward and Outbound functionality to a clean MVC architecture.
• Cleaned up legacy code to improve maintainability and readability.
• Introduced new controllers, models, and views to separate business logic from presentation.
• Refactored existing UI to align with the MVC structure.
• Ensured that existing functionality, including configuration handling and rule processing, remains intact and fully functional after the refactor.