Ladybird/Android: Bind WebSocketService for WebSocket purposes

Similar to the RequestServer, bind this from the WebContentService
implementation and have it work the same way. Deduplicate some code
while we're here.

Ladybird/Android/src/main/cpp/WebSocketService.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2021, Dex♪ <dexes.ttp@gmail.com>
+ * Copyright (c) 2023, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/LexicalPath.h>
+#include <Ladybird/Utilities.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/EventLoop.h>
+#include <LibCore/LocalServer.h>
+#include <LibCore/System.h>
+#include <LibFileSystem/FileSystem.h>
+#include <LibIPC/SingleServer.h>
+#include <LibTLS/Certificate.h>
+#include <WebSocket/ConnectionFromClient.h>
+
+// FIXME: Share b/w RequestServer and WebSocket
+ErrorOr<String> find_certificates(StringView serenity_resource_root)
+{
+    auto cert_path = TRY(String::formatted("{}/res/ladybird/cacert.pem", serenity_resource_root));
+    if (!FileSystem::exists(cert_path)) {
+        auto app_dir = LexicalPath::dirname(TRY(Core::System::current_executable_path()).to_deprecated_string());
+
+        cert_path = TRY(String::formatted("{}/cacert.pem", LexicalPath(app_dir).parent()));
+        if (!FileSystem::exists(cert_path))
+            return Error::from_string_view("Don't know how to load certs!"sv);
+    }
+    return cert_path;
+}
+
+ErrorOr<int> service_main(int ipc_socket, int fd_passing_socket)
+{
+    // Ensure the certificates are read out here.
+    DefaultRootCACertificates::set_default_certificate_path(TRY(find_certificates(s_serenity_resource_root)));
+    [[maybe_unused]] auto& certs = DefaultRootCACertificates::the();
+
+    Core::EventLoop event_loop;
+
+    auto socket = TRY(Core::LocalSocket::adopt_fd(ipc_socket));
+    auto client = TRY(WebSocket::ConnectionFromClient::try_create(move(socket)));
+    client->set_fd_passing_socket(TRY(Core::LocalSocket::adopt_fd(fd_passing_socket)));
+
+    return event_loop.exec();
+}