feat: allow policies.json management via unwrapped package override (#49)

In previous iterations the browser were forced to have disabled updates but this
might create an undesirable behavior in tools like 1Password as you can see here:
https://github.com/0xc000022070/zen-browser-flake/issues/48

So I'm allowing to override the browser policies. This will only work for unwrapped packages.

hm-module.nix

@@ -3,8 +3,8 @@
   self,
   name,
 }: {
-  pkgs,
   config,
+  pkgs,
   lib,
   ...
 }: let
@@ -38,9 +38,10 @@ in {
   config = lib.mkIf config.programs.zen-browser.enable {
     programs.zen-browser = {
       package = self.packages.${pkgs.stdenv.system}.${name};
-      policies = {
-        DisableAppUpdate = lib.mkDefault true;
-        DisableTelemetry = lib.mkDefault true;
+      # This does not work, the package can't build using these policies
+      policies = lib.mkDefault {
+        DisableAppUpdate = true;
+        DisableTelemetry = true;
       };
     };
   };

package.nix

@@ -2,6 +2,7 @@
   name,
   variant,
   desktopFile,
+  policies ? {},
   lib,
   stdenv,
   config,
@@ -37,13 +38,11 @@
     aarch64-linux = "linux-aarch64";
   };
 
-  policies =
-    {
-      DisableAppUpdate = true;
-    }
-    // config.firefox.policies or {};
+  firefoxPolicies =
+    (config.firefox.policies or {})
+    // policies;
 
-  policiesJson = writeText "firefox-policies.json" (builtins.toJSON {inherit policies;});
+  policiesJson = writeText "firefox-policies.json" (builtins.toJSON {policies = firefoxPolicies;});
 
   pname = "zen-${name}-bin-unwrapped";
 in