Give access to xdg-download due to skin changer

[SystemlessDev]

The skin changer in the launcher is quite useless without permission to any directories. The average joe will most likely put their skin in their downloads folder, so allowing the launcher read only access to that folder just seems natural.

[flathubbot]

Started test build 110008

[flathubbot]

Build 110008 successful To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/107632/com.mojang.Minecraft.flatpakref

[AsciiWolf]

Thanks!