linux: build hardened kernel with matching releases

Until now we merged kernel updates even if no hardened versions were
available yet. On one hand we don't want to delay patch-level updates,
on the other hand users of hardened kernels have frequent breakage now[1].

This change aims to provide a solution this issue:

* The hardened patchset now references the kernel version it's released
  for (including a sha256 hash for the fixed-output path of the source
  tarball).
* The `hardenedKernelFor`-function doesn't just append hardened patches
  now, but also overrides version & src to match the kernel version the
  patch was built & tested for.

Refs #140281

[1] https://hydra.nixos.org/job/nixos/trunk-combined/nixpkgs.linuxPackages_hardened.kernel.x86_64-linux/all

(cherry picked from commit bb5aa0109b6db98a2e0a7ba88f5e0287e2374384)

pkgs/os-specific/linux/kernel/patches.nix

@@ -47,10 +47,11 @@
   cpu-cgroup-v2 = import ./cpu-cgroup-v2-patches;
 
   hardened = let
-    mkPatch = kernelVersion: src: {
+    mkPatch = kernelVersion: { version, sha256, patch }: let src = patch; in {
       name = lib.removeSuffix ".patch" src.name;
       patch = fetchurl (lib.filterAttrs (k: v: k != "extra") src);
       extra = src.extra;
+      inherit version sha256;
     };
     patches = builtins.fromJSON (builtins.readFile ./hardened/patches.json);
   in lib.mapAttrs mkPatch patches;