The goal of this function is to make it possible to build a kernel with a user provided .config.
As a secondary goal, it will extract NixOS-relevant features from the config automatically.
As a tertiary goal, the build will aim to be simpler than the current generic kernel builder.sh.
Unfortunately, that simplicity is offset by the complexity of the feature extraction, especially since nix segfaults when trying to split the file into lines (so an import from a derivation is used)
