CatDog: Help the user debug their programs

This adds helpful speech bubbles to CatDog. CatDog just wants to
help, that's all.

Userland/Demos/CatDog/SpeechBubble.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gunnar@beutner.name>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGUI/Widget.h>
+
+class SpeechBubble final : public GUI::Widget {
+    C_OBJECT(SpeechBubble);
+
+public:
+    virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void mousedown_event(GUI::MouseEvent&) override;
+
+    Function<void()> on_dismiss;
+
+private:
+    SpeechBubble() = default;
+};