feat: Enable fingerprint authentication for login screen

- Added new `default.nix` file in `dell/xps/15-9530/fingerprint` directory
- Enabled `services.fprintd` service in the configuration
- Set up `tod` driver for fingerprint scanner
- Allowed password authentication for initial password login
- Configured fingerprint authentication for GDM login screen

[dell/xps/15-9530/fingerprint/default.nix]
- Add a new file `default.nix` in the `dell/xps/15-9530/fingerprint` directory
- Enable the `services.fprintd` service in the configuration
- Set up the `tod` driver for the fingerprint scanner
- Configured fingerprint authentication for the initial password login
- Configure fingerprint authentication for the GDM login screen

dell/xps/15-9530/fingerprint/default.nix

@@ -0,0 +1,40 @@
+{ pkgs, lib, config, ... }: {
+
+  environment.systemPackages = [
+
+  ];
+
+  services.fprintd = {
+    enable = true;
+    tod = {
+      enable = true;
+      driver = pkgs.libfprint-2-tod1-goodix;
+    };
+
+  };
+
+  # Used to allow a password login on first login as an alternative to just a fingerprint
+  security.pam.services.login.fprintAuth = false;
+  # similarly to how other distributions handle the fingerprinting login
+  security.pam.services.gdm-fingerprint =
+    lib.mkIf (config.services.fprintd.enable) {
+      text = ''
+        auth       required                    pam_shells.so
+        auth       requisite                   pam_nologin.so
+        auth       requisite                   pam_faillock.so      preauth
+        auth       required                    ${pkgs.fprintd}/lib/security/pam_fprintd.so
+        auth       optional                    pam_permit.so
+        auth       required                    pam_env.so
+        auth       [success=ok default=1]      ${pkgs.gnome.gdm}/lib/security/pam_gdm.so
+        auth       optional                    ${pkgs.gnome.gnome-keyring}/lib/security/pam_gnome_keyring.so
+
+        account    include                     login
+
+        password   required                    pam_deny.so
+
+        session    include                     login
+        session    optional                    ${pkgs.gnome.gnome-keyring}/lib/security/pam_gnome_keyring.so auto_start
+      '';
+    };
+
+}