waybar: refactor

[AndersonTorres]

• Reorder argument list
• Use rec-less, overlay-style overridable recursive attributes (in effect since stdenv.mkDerivation: overlay style overridable recursive attributes #119942);
• Use pushd/popd instead of subshell
• Use lib.mesonEnable and lib.mesonBool
• Indentation
• Remove nested with

Description of changes

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/)
• 23.11 Release Notes (or backporting 23.05 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
• Fits CONTRIBUTING.md.

[minijackson]

Now, I'm a bit confused about this PR. No checkbox was ticked, so I don't know the extent of the tests you did, and it was merged only a few hours later, without any other comment by someone else.

I was planning on reviewing it when I got notified, but simply did not have the time to finish work and go home before the PR was merged. I would probably have accepted, I do like the changes, but you can guess my surprise when I found out that a package that I maintain got refactored without any approval of any of the maintainers.

[AndersonTorres]

I judged the reword as mostly equivalent and needed no more than a local testing and an all-green CI.

Sorry by my haste. I was on a small hurry for merging some already approved PRs.