Implement libsolv for dependency resolution

[DavHau]

libsolv seems more sophisticated than resolvelib. It is used in a number of other projects, for example https://github.com/mamba-org/mamba.

Resolvelib is made for pip and has to work around pip's restrictions. Pip for example does not have an offline dependency DB which is why resolvelib cannot be an optimal algorithm.

With libsolv it should be possible to harvest all advantages the dependency DB can give us and also report better errors in case of a resolution problem.