Add support for XDG game list

[MCMic]

Hello,

I wish to launch native games with emulationstation as well.
For now I use this little hack: https://gitlab.mugoreve.fr/Come/xdg2emulationstation/tree/master

But it would be way better if emulation station had a way to fetch itself the game from the XDG information. I’m pretty sure there are libraries for this in C++ as well.

(The main problem of my script is it needs to be run each time you want to update the game list and you lose info like last time you played the game at each of those updates)