firefox: add smartcard support through opensc

[gardspirito]

I'm an idiot who messed up with git and unintentionally posted multiple review requests. Please, forgive ne.

Motivation for this change

Conditionally provides Frefox with access to opensc library and includes the respective PKCS#11 module via policies.json. This allows to use external PKCS#11-based devices such as smartcards with Firefox.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Relase 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.

[gardspirito]

Ping @lovesegfault

[gardspirito]

Also, I'm new to nixpkgs, so I don't know whether this should be fixed here, but smart cards support also requires services.pcscd.enable = true;.

[lovesegfault]

Also, I'm new to nixpkgs, so I don't know whether this should be fixed here, but smart cards support also requires services.pcscd.enable = true;.

You can add a comment in the pkg derivation if you want.

[lovesegfault]

Alright, this is looking good!

Please squash the commits and I'll merge it. Message should read:

firefox: add smartcard support through opensc

[gardspirito]

Done.

Please, don't ask any questions... I want to forget about this nightmare and my incompetence.

[lovesegfault]

Thanks for the contribution!