Ladybird: Move Qt-specific classes and functions to a Qt subdirectory

This will help a lot with developing chromes for different UI frameworks
where we can see which helper classes and processes are really using Qt
vs just using it to get at helper data.

As a bonus, remove Qt dependency from WebDriver.

Ladybird/Qt/LocationEdit.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2023, Cameron Youell <cameronyouell@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <QLineEdit>
+
+namespace Ladybird {
+
+class LocationEdit final : public QLineEdit {
+    Q_OBJECT
+public:
+    explicit LocationEdit(QWidget*);
+
+private:
+    virtual void focusInEvent(QFocusEvent* event) override;
+    virtual void focusOutEvent(QFocusEvent* event) override;
+
+    void highlight_location();
+};
+
+}