bitwarden-desktop: add darwin support and do minor refactor

[TomaSajt]

cc: @amarshall

Alternative to #303417
Alternative to #368638

This PR adds darwin support to bitwarden-desktop.

The new platform-triple patch reduces the complexity of the derivation by not having to do renaming in postBuild, which would have got more complicated if we had to handle darwin too.

In the install phase I used ${lib.optionalString ...} to do conditional stuff. If you prefer to use ++ lib.optionalString ... ++ I can swap it out.

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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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.

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[amarshall]

At first glance, this looks pretty good—thanks! Will get to full review and testing soon-ish.

[damidoug]

Im using this version on darwin, its working cool.

I just recommend add the updater to allow we update bitwarden from the app.

[amarshall]

Installing via Nix is fundamentally incompatible with in-app updates, as either the app will try and fail to update because the store is read-only, or try and succeed and corrupt the store. If it does succeed, a future apply of the NixOS (or nix-darwin or home-manager) config may also rollback the update. TL;DR: if you want in-app updates outside of Nix, do not install via Nix.

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I should hopefully be able to look at this some more this weekend.

[TomaSajt]

Added a patch which makes the app just open the releases page when an update is available.
This is done by forcing a canUpdate to false.

If it's better, I can make it just do nothing.