Carry over discussion from IRC #nixos-dev and #108934. Inspired by the doc change in c06b2b3 recommending top-level usage of lib over stdenv.lib, we want to reduce confusion for newcomers and unnecessary complexity by making lib the canonical way to access the Nix library. We may still want to keep stdenv.lib to not break external code, and place a trace or similar at its definition site.

$ nix-shell -p ag --run 'ag "stdenv\.lib" -l | wc -l'
11783

There are over 11000 files where stdenv.lib occurs at least once. Beyond splitting this change across multiple PRs, in what ways can the change be automated?

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