Now that the GML formatter is both perserving comments and also mostly
agrees to the existing GML style, it can be used to auto-format all the
GML files in the system. This commit does not only contain the scripts
for running the formatting on CI and the pre-commit hook, but also
initially formats all the existing GML files so that the hook is
successfull.
This is an application analogous to WidgetGallery, in that it tests
various capabilities of LibGUI models. Right now it is pretty bare, but
as more work towards LibGUI models is done regarding persistent model
indices, more demos will be added.
