WebDriver: Add new WebDriver service

WebDriver aims to implement the WebDriver specification found at
https://w3c.github.io/webdriver/webdriver-spec.html . It's an HTTP
server that can create Browser sessions and control them.

Co-authored-by: Florent Castelli <florent.castelli@gmail.com>

Userland/Services/WebDriver/Session.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2022, Florent Castelli <florent.castelli@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/JsonValue.h>
+#include <AK/RefPtr.h>
+#include <WebDriver/BrowserConnection.h>
+#include <WebDriver/HttpError.h>
+#include <unistd.h>
+
+namespace WebDriver {
+
+class Session {
+public:
+    Session(unsigned session_id, NonnullRefPtr<Client> client);
+    ~Session();
+
+    unsigned session_id() const { return m_id; }
+
+    struct Window {
+        String handle;
+        bool is_open;
+    };
+
+    HashMap<String, NonnullOwnPtr<Window>>& get_window_handles() { return m_windows; }
+    Optional<Window*> get_window_object() { return m_windows.get(m_current_window_handle); }
+    String get_window() { return m_current_window_handle; }
+
+    ErrorOr<void> start();
+    ErrorOr<void> stop();
+    ErrorOr<void, Variant<HttpError, Error>> delete_window();
+    ErrorOr<JsonValue, HttpError> post_url(JsonValue const& url);
+    ErrorOr<JsonValue, HttpError> get_title();
+
+private:
+    NonnullRefPtr<Client> m_client;
+    bool m_started { false };
+    unsigned m_id { 0 };
+    HashMap<String, NonnullOwnPtr<Window>> m_windows;
+    String m_current_window_handle;
+    RefPtr<Core::LocalServer> m_local_server;
+    RefPtr<BrowserConnection> m_browser_connection;
+};
+
+}