Seed packaging for Fedora/CentOS

I started building rpm packages for Radicle seed on COPR recently, so that I don’t need to deal with the ever growing build directories on the server. The repository is in a working state and I’ll keep bumping it as new commits land upstream (with no official versions yet, I’m just using 0.0.0-x).

Feel free to use and report any issues.

(updates are manual, so they may lag a bit)