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/InspectorWidget.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2022, MacDue <macdue@dueutil.tech>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "ModelTranslator.h"
+#include "WebContentView.h"
+#include <AK/Optional.h>
+#include <AK/StringView.h>
+#include <LibWeb/CSS/Selector.h>
+#include <QWidget>
+
+class QTreeView;
+class QTableView;
+
+namespace Ladybird {
+
+class InspectorWidget final : public QWidget {
+    Q_OBJECT
+public:
+    InspectorWidget();
+    virtual ~InspectorWidget() = default;
+
+    struct Selection {
+        i32 dom_node_id { 0 };
+        Optional<Web::CSS::Selector::PseudoElement> pseudo_element {};
+        bool operator==(Selection const& other) const = default;
+    };
+
+    bool dom_loaded() const { return m_dom_loaded; }
+
+    void set_selection(Selection);
+    void clear_selection();
+
+    void select_default_node();
+
+    void clear_dom_json();
+    void set_dom_json(StringView dom_json);
+
+    void set_accessibility_json(StringView accessibility_json);
+
+    void load_style_json(StringView computed_style_json, StringView resolved_style_json, StringView custom_properties_json);
+    void clear_style_json();
+
+    Function<ErrorOr<WebContentView::DOMNodeProperties>(i32, Optional<Web::CSS::Selector::PseudoElement>)> on_dom_node_inspected;
+    Function<void()> on_close;
+
+private:
+    void set_selection(GUI::ModelIndex);
+    void closeEvent(QCloseEvent*) override;
+
+    Selection m_selection;
+
+    ModelTranslator m_dom_model {};
+    ModelTranslator m_accessibility_model {};
+    ModelTranslator m_computed_style_model {};
+    ModelTranslator m_resolved_style_model {};
+    ModelTranslator m_custom_properties_model {};
+
+    QTreeView* m_dom_tree_view { nullptr };
+
+    bool m_dom_loaded { false };
+    Optional<Selection> m_pending_selection {};
+};
+
+}