For a long time, curious problems with inter-dependent packages in the
home: projects appeared, depending on the order of the <path/> entries
in the project meta. It has now become clear, that this was due to an
unfortunate misunderstanding by us in the way the OBS expands nested
<path/> dependencies: Only the very last entry is recursively expanded!

Fix by manually expanding the other entries. Now, multi-package
experiments within different home: project repositories should be
possible with correct inter-home: project dependencies.

This can be used to list all unresolved dependencies of the built RPMs

Use common functionality of other commands, add --diff and --remove-old
as arguments.

Also: Rename to ..._cluster*s*_project, matching the actual name of the
project, 'clusters'.

Otherwise, the sub-projects have both hostlabels as constraints. Was not
enforced like this before 2021-10-29. But now something triggered this,
possibly it was always ment to be like this? Only thing that happened
today was an OOM initiated kill of bs_sched on obs-backend, that maybe
re-read information that was stale for a long time.

Oh well...

This makes it easier in the spec files, e.g. in conditionals

Also, colorful diffs

It was incorrectly set also set for the "System" repository there, which
caused software there to be built incorrectly (with the micro arch
flags) and in the wrong location