Hook into the evaluation to cache to cache the evaluation of flake members (stuff like `(builtins.getCache foo).bar.baz`). Also replaces the old eval cache that was used at the cli level.
(cherry picked from commit 2c692a3b14)
2c692a3b14
All plugins in plugin-files will be dlopened, allowing them to statically construct instances of the various Register* types Nix supports.