rpm repo via metalink

RPM repo files contain a metalink defination in the repo definition so users don't get stuck with stale mirrors in their config.

This has existed a significant time and would benefit all yum/dnf based users.

This effectively acts as a redirection service on our infrastructure with download redirection to the up to date mirrors. It also acts as a locality detector in the same way as the current repo, except its dynamic per user connection rather than just configuration time.

The source code is https://github.com/fedora-infra/mirrormanager2

Documentation https://mirrormanager.readthedocs.io/en/latest/deployment.html refers to base config https://github.com/fedora-infra/mirrormanager2/blob/master/utility/mirrormanager2.cfg.sample