This commit was created by a combination of scripts and tools:
- an ast-grep script to prefix things in meta with `lib.`,
- a modified nixf-diagnose / nixf combination to remove unused `with
lib;`, and
- regular nixfmt.

Co-authored-by: Wolfgang Walther <walther@technowledgy.de>

Follow-up to #394797.

Signed-off-by: Fernando Rodrigues <alpha@sigmasquadron.net>

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

nix run nixpkgs#silver-searcher -- -G '\.nix$' -0l 'description.*"([Tt]he)? ' pkgs \
  | xargs -0 nix run nixpkgs#gnused -- -i '' -Ee 's/(description.*")[Tt]he (.)/\1\U\2/'

And a complete rewite of this somewhat old expression.

Because tohl disappeared (last seen 2021-01-28).