Motivation for this change

We only have cfq and noop, so add other I/O schedulers (deadline, mq-deadline, mq-kyber and mq-bfq). Values are default ones, except the mq-bfq, which is disabled by default, but it makes no harm to build it as module for early adopters.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.