gopass: Support passAlias parameter in derivation

Add a `passAlias` to `gopass` derivation, similarly to how there's `viAlias` parameter supported by vim/neovim derivations.
Apart from convenience this is also necessary for e.g. making `docker-credential-helpers` work without patching the latter - the package uses `pass` executable from `PATH` https://github.com/docker/docker-credential-helpers/blob/f78081d1f7fef6ad74ad6b79368de6348386e591/pass/pass_linux.go#L67. By setting `passAlias` to `true` (e.g. via overlays like so: https://github.com/rvolosatovs/infrastructure/blob/94971f34db9df79b6666e626fa52840eb1fee840/nixpkgs/overlays.nix#L315-L317), secure Docker authentication via `gopass` "just works"™

pkgs/tools/security/gopass/default.nix

@@ -1,4 +1,11 @@
-{ stdenv, buildGoModule, fetchFromGitHub, git, gnupg, xclip, wl-clipboard, installShellFiles, makeWrapper }:
+{ stdenv, makeWrapper
+, buildGoModule, fetchFromGitHub, installShellFiles
+, git
+, gnupg
+, xclip
+, wl-clipboard
+, passAlias ? false
+}:
 
 buildGoModule rec {
   pname = "gopass";
@@ -28,6 +35,8 @@ buildGoModule rec {
       $out/bin/gopass completion $shell > gopass.$shell
       installShellCompletion gopass.$shell
     done
+  '' + stdenv.lib.optionalString passAlias ''
+    ln -s $bin/bin/gopass $bin/bin/pass
   '';
 
   postFixup = ''