MacOS support for the wallpaper casks

[tulilirockz]

I love every single wallpaper here and I wanted to use these on my work computer without manually having to add them... Would this be a thing we could do? I wonder if there are similar casks to these already on Homebrew-core.

[castrojo]

Also I know macs have support for timed wallpapers via HEIC, it'd be awesome if we could replicate the timed wallpaper thing for mac people.

[daegalus]

Its doable, we just need use add macos to the list of OS and use on_macos blocks or some_such. Might need to move the linux stuff into on_linux or something.

[daegalus]

https://github.com/Homebrew/homebrew-cask/blob/f87e2b258ef5fbe8900380227a7215d54de104fd/Casks/1/1password-cli.rb#L3 is an example of the OS header.

and here is a small example of on_linux and on_macos https://github.com/Homebrew/homebrew-cask/blob/f87e2b258ef5fbe8900380227a7215d54de104fd/Casks/g/gogs.rb#L2-L8

We just need to add heic animated wallpapers for OSX to our artwork builders, and I need to know where to stick them. I haven't used MacOS in many years.