Swaynag is a replacement of i3-nag for sway. Swaynag is embedded in
Sway's build process albeit it is not an integral part of Sway,
therefore it has been added under `wayland.windowManager.sway` instead
of `programs`. It can be moved at a later time if necessary.
Two unit tests were added validate the module behavior for an empty
configuration and the example configuration.
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.
When setting `...sway.package = null`, the default bar configuration
would throw an error trying to use the bar from the null package.
Logic is added to use the bar from `pkgs.sway` instead of `cfg.package`
if it is null.
Fixes#1714
Using the final package in the `onChange` block broke some use cases.
This restores the old behavior and instead solves the test
dependencies in a different way.
Fixes#1611
This reverts commit 7c3c64208e.
