--accept-flake-config
When setting flake-local options (with the `nixConfig` field), forward these options to the daemon in case we’re using one. This is necessary in particular for options like `binary-caches` or `post-build-hook` to make sense. Fix <https://github.com/NixOS/nix/commit/343239fc8a1993f707a990c2cd54a41f1fa3de99#r44356843>