LibCore: Add Core::debounce(function, timeout)

This is a simple helper to debounce a function call, such as
an event handler. It avoids the function being called until
the event as settled down (i.e. after the timeout).

Userland/Libraries/LibCore/Debounce.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2022, MacDue <macdue@dueutil.tech>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibCore/Timer.h>
+
+namespace Core {
+
+template<typename TFunction>
+auto debounce(TFunction function, int timeout)
+{
+    RefPtr<Core::Timer> timer;
+    return [=]<typename... T>(T... args) mutable {
+        auto apply_function = [=] { function(args...); };
+        if (timer) {
+            timer->stop();
+            timer->on_timeout = move(apply_function);
+        } else {
+            timer = Core::Timer::create_single_shot(timeout, move(apply_function));
+        }
+        timer->start();
+    };
+};
+
+}