The `style` option now also accepts a path instead of a text
configuration.
Keeping up with new Waybar options is annoying, so make the module a
freeform module.
The `modules` option will be removed in release 22.05.
The logic to generate warnings for modules and everything was
removed. I don't want to maintain the code that generates these
warnings anymore.
This option provides a more convenient way to overlay dummy packages.
It also adds a function `config.lib.test.mkStubPackage` that can,
e.g., be used for `package` options.
