ladybird: unstable-2022-07-20 -> unstable-2022-08-14, add nixos test

[fgaz]

Description of changes

Things done

• Built on platform(s)
  • [x] x86_64-linux
  • [ ] aarch64-linux
  • [ ] x86_64-darwin
  • [ ] aarch64-darwin
• [ ] For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• [x] 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
• [x] 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
• [x] Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.11 Release Notes (or backporting 22.05 Release notes)
  • [x] (Package updates) Added a release notes entry if the change is major or breaking
  • [x] (Module updates) Added a release notes entry if the change is significant
  • [x] (Module addition) Added a release notes entry if adding a new NixOS module
  • [x] (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• [x] Fits CONTRIBUTING.md.

[fgaz]

@symphorien can we merge?

edit: I rebased and resolved the conflict

[symphorien]

Sorry I won't have to to review meaningfully

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/1214