Add loop-less disk builder (systemd-repart)

[schaefi]

Description

The current implementation for the disk builder makes use kernel interfaces, meaning the produced devices are created through loop devices as well as the produced file-systems gets mounted and more. Under certain conditions the dependency into the kernel could cause a problem e.g if the calling user has not enough permissions or the environment does not expose access to these interfaces. In this case it would be handy if kiwi could offer a disk builder which does not require kernel interfaces.

The systemd project offers a tool called systemd-repart which implements many parts of the build process without the need for the kernel interfaces. This leads to the idea to write a new builder class that utilizes systemd-repart to build the disk image. systemd-repart is also used in the mkosi image builder from which the idea originates. For reference see make_image():

• https://github.com/systemd/mkosi/blob/main/mkosi/__init__.py#L2621

kiwi needs to implement an interface to systemd-repart and its required input files

[schaefi]

on suse systemd-repart is provided with the systemd-experimental package

[Conan-Kudo]

On RH/Fedora, it's part of the systemd-udev package (yeah, I dunno why, but oh well?).