Add wallpapers for remaining flavors

[uncenter]

Not sure if this is intentional but it seems odd that we are only providing a macchiato wallpaper: https://github.com/catppuccin/opera-gx/blob/main/src/wallpapers/macchiato.png.

[isabelroses]

Its not. But catppuccin/wallpapers got deleted so I have no good source. Happy to accept PRs.