malcontent-ui: split from malcontent

The 0.7.0 update allows us to split the package.

pkgs/development/libraries/malcontent/ui.nix

@@ -0,0 +1,70 @@
+{ stdenv
+, meson
+, ninja
+, pkg-config
+, gobject-introspection
+, wrapGAppsHook
+, glib
+, accountsservice
+, dbus
+, flatpak
+, malcontent
+, gtk3
+, desktop-file-utils
+, polkit
+, glib-testing
+}:
+
+stdenv.mkDerivation rec {
+  pname = "malcontent-ui";
+
+  inherit (malcontent) version src;
+
+  outputs = [ "bin" "out" "dev" ];
+
+  patches = [
+    # Allow installing installed tests to a separate output.
+    ./installed-tests-path.patch
+
+    # Do not build things that are part of malcontent package
+    ./better-separation.patch
+  ];
+
+  nativeBuildInputs = [
+    meson
+    ninja
+    pkg-config
+    gobject-introspection
+    desktop-file-utils
+    wrapGAppsHook
+  ];
+
+  buildInputs = [
+    dbus
+    polkit
+    glib-testing
+    flatpak
+  ];
+
+  propagatedBuildInputs = [
+    accountsservice
+    malcontent
+    glib
+    gtk3
+  ];
+
+  mesonFlags = [
+    "-Dinstalled_tests=true"
+    "-Dinstalled_test_prefix=${placeholder "installedTests"}"
+    "-Duse_system_libmalcontent=true"
+    "-Dui=enabled"
+  ];
+
+  meta = with stdenv.lib; {
+    description = "UI components for parental controls library";
+    homepage = "https://gitlab.freedesktop.org/pwithnall/malcontent";
+    license = licenses.lgpl21Plus;
+    maintainers = with maintainers; [ jtojnar ];
+    platforms = platforms.unix;
+  };
+}