Add ArchUpdater widget and service; update settings for Arch updates

Modules/Bar/Widgets/ArchUpdater.qml

@@ -0,0 +1,49 @@
+import qs.Commons
+import qs.Services
+import qs.Widgets
+
+NIconButton {
+    id: root
+    visible: Settings.data.bar.showArchUpdater && ArchUpdaterService.isArchBased
+    sizeMultiplier: 0.8
+
+    colorBg: Color.mSurfaceVariant
+    colorFg: Color.mOnSurface
+    colorBorder: Color.transparent
+    colorBorderHover: Color.transparent
+
+    icon: !ArchUpdaterService.ready ? "block" : (ArchUpdaterService.busy ? "sync" : (ArchUpdaterService.updatePackages.length > 0 ? "system_update" : "task_alt"))
+
+    tooltipText: {
+        if (!ArchUpdaterService.isArchBased)
+            return "Arch users already ran 'sudo pacman -Syu' for breakfast.";
+        if (!ArchUpdaterService.checkupdatesAvailable)
+            return "Please install pacman-contrib to use this feature.";
+        if (ArchUpdaterService.busy)
+            return "Checking for updates…";
+
+        var count = ArchUpdaterService.updatePackages.length;
+        if (count === 0)
+            return "No updates available";
+
+        var header = count === 1 ? "One package can be upgraded:" : (count + " packages can be upgraded:");
+
+        var list = ArchUpdaterService.updatePackages || [];
+        var s = "";
+        var limit = Math.min(list.length, 10);
+        for (var i = 0; i < limit; ++i) {
+            var p = list[i];
+            s += (i ? "\n" : "") + (p.name + ": " + p.oldVersion + " → " + p.newVersion);
+        }
+        if (list.length > 10)
+            s += "\n… and " + (list.length - 10) + " more";
+
+        return header + "\n" + s;
+    }
+
+    onClicked: {
+        if (!ArchUpdaterService.ready || ArchUpdaterService.busy)
+            return;
+        ArchUpdaterService.runUpdate();
+    }
+}