pythonPackages.unittestCheckHook: align to docs, support dynamic flags in preCheck script

[impl]

Description of changes

In the docs, the flags for the unittestCheckHook are described as belonging in unittestFlags, but it seems that the hook script was expecting them to be set as unittestFlagsArray. In stdenv at least it seems that the *Array variants are used for dynamically configuring the flags in a pre* script, e.g. preCheck = "unittestFlagsArray+=(--foo)", so this PR aligns the script behavior to the docs/stdenv instead of just updating the docs to match the current implementation.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.11 Release Notes (or backporting 22.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[winterqt]

so this PR aligns the script behavior to the docs/stdenv instead of just updating the docs to match the current implementation.

Please do this instead. It looks like I forgot to change the docs after #185430 (comment) -- unittestFlagsArray is correct (for now, anyways).

[impl]

so this PR aligns the script behavior to the docs/stdenv instead of just updating the docs to match the current implementation.

Please do this instead. It looks like I forgot to change the docs after #185430 (comment) -- unittestFlagsArray is correct (for now, anyways).

Ah ok, will do! I'll open a new PR against master since it won't require a mass-rebuild then. Thanks!