211: home-manager fixes r=nrdxp a=nrdxp
- [x] integrate nix-community/home-manager#1880 (to avoid duplicate commits, we'll wait a bit to see if this gets merged)
- [x] don't use all of `systemPackages` for `flk home`
- [x] test home-manager `activationPackage` and `flk home` as part of CI
Co-authored-by: Timothy DeHerrera <tim.deh@pm.me>