Add Plugin Support for melonDS Emulator

📋 Summary

Add official plugin support for melonDS, a highly compatible and accurate Nintendo DS emulator, to streamline setup, configuration, and launching of DS titles from within LaunchBox.

🎯 Feature Overview

• Automatically download and set up melonDS through LaunchBox.

• Associate .nds and .dsi files with melonDS.

• Support built-in configuration for DS screen layout, input mapping, and BIOS/firmware paths.

• Enable per-game settings and multiplayer/Wi-Fi emulation setup where applicable.