plasma: Add sddm-sugar-dark as a theme

packages/themes/sddm/sugar-dark/default.nix

@@ -0,0 +1,32 @@
+{
+  fetchFromGitHub
+, stdenv, formats
+, config ? {}
+}:
+
+# This package works a bit differently as the config needs to be inside the package.
+# Override with config set to the settings you want. See
+# https://github.com/MarianArlt/sddm-sugar-dark/blob/master/theme.conf
+let
+  iniFmt = formats.ini {};
+  configFile = iniFmt.generate "theme.conf" config;
+in stdenv.mkDerivation rec {
+  pname = "sddm-sugar-dark";
+  version = "1.2";
+
+  src = fetchFromGitHub {
+    owner = "MarianArlt";
+    repo = "sddm-sugar-dark";
+    rev = "v${version}";
+    sha256 = "0gx0am7vq1ywaw2rm1p015x90b75ccqxnb1sz3wy8yjl27v82yhb";
+  };
+
+  dontBuild = true;
+
+  installPhase = ''
+    mkdir -p $out/usr/share/sddm/themes/sugar-dark
+
+    cp -r metadata.desktop Main.qml Background.jpg Components Assets $out/usr/share/sddm/themes/sugar-dark
+    ln -s ${configFile} $out/usr/share/sddm/themes/sugar-dark/theme.conf
+  '';
+}