repomd - rpm repo metdata

WIP A gigantic piece of in porgres and unstructured, mostly broken code WIP

Client

A client spec that includes the a simple toml-like format describing the remote end of the repository.

Server

• Provide repo metadata compliant metadata from an arbitrary source via struct Repo.
• Load createrepo repositories into memory

Spec

Follows https://en.opensuse.org/openSUSE:Standards_Rpm_Metadata and assures real life functionality with guaranteed compat with Fedora 32+.`