add get-nixos-kconfig nix script

[o8opi]

Hello,

This nix script, when run with nix-build get-nixos-kconfig.nix will output 3 kernel configuration files (linux_latest, linux_hardened, and the linux_lts) for NixOS

Has been tested on Ubuntu 20.04

#63 relevant

[codecov-commenter]

Codecov Report

Merging #77 (6149a3e) into master (6211b68) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #77   +/-   ##
=======================================
  Coverage   92.79%   92.79%           
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  Files           3        3           
  Lines         736      736           
  Branches      171      171           
=======================================
  Hits          683      683           
  Misses         26       26           
  Partials       27       27           

Flag	Coverage Δ
functional_test	92.79% <ø> (ø)

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[a13xp0p0v]

Thanks a lot, @o8opi!

It's merged.

I also generated the NixOS kernel configs using nix-build get-nixos-kconfig.nix: 0267c39