Add Plugin Support for Mesen 2 Emulator

📋 Summary

Introduce official plugin support for Mesen 2, a high-accuracy multi-system emulator (NES, SNES, GB/GBC), allowing for seamless setup, game import, and configuration within LaunchBox.

🎯 Feature Overview

This plugin would:

• Automatically download and install Mesen 2 via LaunchBox.

• Enable system-specific emulator settings directly in the LaunchBox UI.

• Detect supported ROM types (NES, SNES, GB/GBC) and assign Mesen 2 accordingly.

• Provide support for Mesen’s built-in rewind, overclocking, HD packs, and debugging tools.