Nix formatting team: Treewide Nixpkgs formatting

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Nix formatting team: Full Nixpkgs reformat

After the previous partial Nixpkgs reformat, the Nix formatting team is now ready for follow-up: To fully standardise formatting in Nixpkgs! Highlights: All files will be formatted using a pinned version the official Nix formatter, aka pkgs.nixpkgs-rfc-format. CI will enforce this going forward, ensuring that all files continue to be formatted consistently. Inside Nixpkgs’ nix-shell/nix develop, you will be able to run treefmt to get the right formatting on all files. You can also …