plugins/desktop-widgets: create a new "desktop" widget plugin type

- Draggable per-monitor background layer widgets
- Add basic dms version checks on plugins
- Clock: built-in clock desktop plugin
- dgop: built-in system monitor desktop plugin

quickshell/PLUGINS/ExampleDesktopClock/DesktopClockSettings.qml

@@ -0,0 +1,45 @@
+import QtQuick
+import qs.Common
+import qs.Modules.Plugins
+
+PluginSettings {
+    id: root
+    pluginId: "exampleDesktopClock"
+
+    SelectionSetting {
+        settingKey: "clockStyle"
+        label: I18n.tr("Clock Style")
+        options: [
+            {
+                label: I18n.tr("Analog"),
+                value: "analog"
+            },
+            {
+                label: I18n.tr("Digital"),
+                value: "digital"
+            }
+        ]
+        defaultValue: "analog"
+    }
+
+    ToggleSetting {
+        settingKey: "showSeconds"
+        label: I18n.tr("Show Seconds")
+        defaultValue: true
+    }
+
+    ToggleSetting {
+        settingKey: "showDate"
+        label: I18n.tr("Show Date")
+        defaultValue: true
+    }
+
+    SliderSetting {
+        settingKey: "backgroundOpacity"
+        label: I18n.tr("Background Opacity")
+        defaultValue: 50
+        minimum: 0
+        maximum: 100
+        unit: "%"
+    }
+}