refactor: (Framemode) Added DeferredAction for dbar/dock state handling

quickshell/Common/DeferredAction.qml

@@ -0,0 +1,55 @@
+import QtQuick
+
+Item {
+    id: root
+
+    visible: false
+    width: 0
+    height: 0
+
+    property int interval: 0
+    property bool pending: false
+
+    signal triggered
+
+    function schedule() {
+        if (!root.enabled || root.pending)
+            return;
+        root.pending = true;
+        deferTimer.restart();
+    }
+
+    function restart() {
+        if (!root.enabled)
+            return;
+        root.pending = true;
+        deferTimer.restart();
+    }
+
+    function flush() {
+        if (!root.pending)
+            return;
+        deferTimer.stop();
+        root.pending = false;
+        root.triggered();
+    }
+
+    function cancel() {
+        deferTimer.stop();
+        root.pending = false;
+    }
+
+    onEnabledChanged: {
+        if (!enabled)
+            cancel();
+    }
+
+    Timer {
+        id: deferTimer
+        interval: root.interval
+        repeat: false
+        onTriggered: root.flush()
+    }
+
+    Component.onDestruction: cancel()
+}