Move wallpaper to theme.wallpaper

Change-Id: I64843a4ea123c8b3a5906824aa194f49f526d7db
Reviewed-on: https://git.clicks.codes/c/Chimera/NixFiles/+/392
Reviewed-by: Samuel Shuert <coded@clicks.codes>
Tested-by: Skyler Grey <minion@clicks.codes>
2 files changed