Set PrefersNonDefaultGPU for hybrid devices

With the Property 'PrefersNonDefaultGPU', you can signal to dekstop environments like GNOME that you want to run the application using the more powerful secondary graphics card, if such a card is available. Specification: https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s06.html

With this change, you won't have to include a special prime-run script.

program_info/org.polymc.PolyMC.desktop.in

@@ -7,5 +7,6 @@ Terminal=false
 Exec=@Launcher_APP_BINARY_NAME@
 StartupNotify=true
 Icon=org.polymc.PolyMC
+PrefersNonDefaultGPU=true
 Categories=Game;
 Keywords=game;minecraft;launcher;