Build specific targets for packaging

We now clearly define targets that packagers can use to build packages with minimal dependencies.

• There should be a main package disman which comes with libraries, service and command line utility.
• The disman-randr, disman-kwinft, disman-wlroots, disman-kwayland packages can depend on this package and provide integration with X11 or one specific type of Wayland compositor.

For example for the KWinFT compositor the disman and disman-kwinft packages should be installed. For Sway instead of a disman-kwinft package a disman-wlroots package should be provided.

Besides that we bump requirements some cleanup changes to the build system we now