Ability to use a standalone image as a theme

[DraconicNEO]

I think it would be a good idea to allow for people to use standalone images as a theme without needing to compile them as a .nxtheme file.
I feel like this would make it much easier for people to make and install their own themes with only slight drawbacks.

Since these theme files really only contain a custom layout and the image I feel like this could work with the only requirement being that you would need to select where the theme is installed (which part of the menu) and using that approach you wouldn't be able to have custom layouts.

Some people might think it's pointless if you can't have a custom layout but since there are many themes that don't have custom layouts themselves I think it's a sacrifice that's worth it considering this simplifies the process by not requiring that you create specific themes if they don't have a custom layout.