Removes the roll-your-own-broken-attribute that `disabled` was. The
advantage of `meta.broken`: It can be caught and properly handled by CI,
while the custom `throw` can not.

After final improvements to the official formatter implementation,
this commit now performs the first treewide reformat of Nix files using it.
This is part of the implementation of RFC 166.

Only "inactive" files are reformatted, meaning only files that
aren't being touched by any PR with activity in the past 2 months.
This is to avoid conflicts for PRs that might soon be merged.
Later we can do a full treewide reformat to get the rest,
which should not cause as many conflicts.

A CI check has already been running for some time to ensure that new and
already-formatted files are formatted, so the files being reformatted here
should also stay formatted.

This commit was automatically created and can be verified using

    nix-build https://github.com/infinisil/treewide-nixpkgs-reformat-script/archive/a08b3a4d199c6124ac5b36a889d9099b4383463f.tar.gz \
      --argstr baseRev b32a0943687d2a5094a6d92f25a4b6e16a76b5b7
    result/bin/apply-formatting $NIXPKGS_PATH

to handle derivations that are not registered or updated on
luarocks.org, for instance neovim plugins.

propagatedBuildInputs was completely overridden in the process

- Lua packages now consistently use LUA_PATH/LUA_CPATH rather than a mix
  of those and NIX_LUA_PATH/NIX_LUA_CPATH
- Lua libraries are now consistently only added to the search path
variables if:
    1) The library actually has a corresponding directory to search
    2) The library is not already present in the search path
  This should help prevent the search paths from growing overly large
- Fixed bugs in some path helpers
- Changed the affected shell script indentation to 2 spaces; nixpkgs
  shell scripts are inconsistently split between 2 and 4 space
  indentation, but 2 matches better with the Nix expressions, so IMO it
  makes more sense

* lua: add withPackages function

First step towards more automation similar to the haskell backend.
Follow up of https://github.com/NixOS/nixpkgs/pull/33903

The LUA_PATH and LUA_CPATH variables are needed to load libraries.
This setupHook exports them to the environment.