Reformat repository using new nixfmt-rfc-style.
Instead of having to manually stub packages that should not be downloaded we instead automatically stub all packages (except a small list of whitelisted ones). Tests can re-introduce the real package by using the `realPkgs` module argument.
* ranger: stub tests * alacritty: stub tests * broot: stub tests * zsh: stub tests * vim-vint: stub tests
Fixes tests that are affected by <https://github.com/NixOS/nixpkgs/pull/333744>.
