RFC: Feat: add autoremove

[Lunarequest]

This is a request for comment on a zypper autoremove command. As a system in updated during its life cycle packages can get left behind. While zypper has rm --cleap-deps and dup --remove-orphaned both have short comings. rm only handles the package passed to it and removing orphans can remove packages a user explicitly built and installed themselves.

To bring zypper inline with the wider linux package manager system(dnf, apt/apt-get) I added a zypper autoremove command. This is code does require reworking of some parts but as it stands this will clean up unneeded and orphaned packages based on flags passed.

Thanks @janvhs who helped debug some issues with the code

[afaerber]

It looks like RCF in the title meant RFC? If you don't want it to be merged yet, you should mark it as draft, which prevents that. Otherwise just remove RFC from title and description, in case maintainers don't require changes and would like to merge it.

[Lunarequest]

It looks like RCF in the title meant RFC? If you don't want it to be merged yet, you should mark it as draft, which prevents that. Otherwise just remove RFC from title and description, in case maintainers don't require changes and would like to merge it.

ah thanks I didn't realize that I typoed RFC, I'll move it to a draft for now, I believe it should be fine to just merge it, in the current state.

[afaerber]

Appreciate this Hackweek project!
Some minor nits pointed out inline.

[mlandres]

In fact a rm --cleap-deps without arguments is WIP together with commands to allow manipulating the auto-installed status of packages. The later is needed to be able to tune the clean-deps result because no user-requested packages should be removed here. Also --cleap-deps in install/update commands to clean in the dependency tree of update packages. A dedicated autoremove command should not be needed or become just an alias for rm --cleap-deps.

The kind of downside of your approach is that it is zypper only and that it's not under direct control of the resolver. I.e. you pass explicit remove requests for packages based on a previous computation rather than asking the resolver itself to compute the job. Implemented in libzypp, the job will become available to YAST and PK as well.