Override callPackage to statify executables

[Aver1y]

This has the advantage of enabling us to just use survey.haskellPackages.callPackage, callCabal2nix and developPackage directly and have them generate static executables.

Note that this depends on NixOS/nixpkgs#90271, so you don't want to merge this right now (hence the draft). So before merging we'd want to wait for that to be merged and update the pinned nixpkgs to some rev after that or backport the patch.