mozillavpn: add qtwayland to build inputs

[teutat3s]

Description of changes

This fixes the app not launching in a wayland environment.

❯ env | grep '^QT_'
QT_QPA_PLATFORMTHEME=gtk2
QT_STYLE_OVERRIDE=gtk2
QT_QPA_PLATFORM=wayland
...

❯ mozillavpn
Aborted (core dumped)

~/.local/share/mozillavpn.log showed:

Warning: Could not find the Qt platform plugin "wayland" in ""
Error: This application failed to start because no Qt platform plugin could be initialized. 
Reinstalling the application may fix this problem. 
Available platform plugins are: linuxfb, minimal, eglfs, minimalegl, vkkhrdisplay, xcb, vnc, offscreen.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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.

---

Add a 👍 reaction to pull requests you find important.

[andersk]

I’m not opposed, although it would be better to address this for all Qt apps at once rather than piecemeal:

• #269674

[wegank]

That probably won't happen soon, as a lot of Qt apps are CLI-only and don't require Xorg or Wayland libraries.

[github-actions]

Successfully created backport PR for release-23.11:

• [Backport release-23.11] mozillavpn: add qtwayland to build inputs #301384