refactor: Coroutine based webserver (#1699)

Code of new coroutine-based web server. The new server is not connected
to Clio and not ready to use yet.
For #919.

tests/common/util/TestHttpClient.hpp

@@ -0,0 +1,99 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2023, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/spawn.hpp>
+#include <boost/asio/ssl/verify_context.hpp>
+#include <boost/beast/core/flat_buffer.hpp>
+#include <boost/beast/core/tcp_stream.hpp>
+#include <boost/beast/http/field.hpp>
+#include <boost/beast/http/message.hpp>
+#include <boost/beast/http/string_body.hpp>
+
+#include <chrono>
+#include <expected>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+struct WebHeader {
+    WebHeader(boost::beast::http::field name, std::string value);
+
+    boost::beast::http::field name;
+    std::string value;
+};
+
+struct HttpSyncClient {
+    static std::string
+    post(
+        std::string const& host,
+        std::string const& port,
+        std::string const& body,
+        std::vector<WebHeader> additionalHeaders = {}
+    );
+
+    static std::string
+    get(std::string const& host,
+        std::string const& port,
+        std::string const& body,
+        std::string const& target,
+        std::vector<WebHeader> additionalHeaders = {});
+};
+
+struct HttpsSyncClient {
+    static bool
+    verify_certificate(bool /* preverified */, boost::asio::ssl::verify_context& /* ctx */);
+
+    static std::string
+    syncPost(std::string const& host, std::string const& port, std::string const& body);
+};
+
+class HttpAsyncClient {
+    boost::beast::tcp_stream stream_;
+    boost::beast::flat_buffer buffer_;
+
+public:
+    HttpAsyncClient(boost::asio::io_context& ioContext);
+
+    std::optional<boost::system::error_code>
+    connect(
+        std::string_view host,
+        std::string_view port,
+        boost::asio::yield_context yield,
+        std::chrono::steady_clock::duration timeout
+    );
+
+    std::optional<boost::system::error_code>
+    send(
+        boost::beast::http::request<boost::beast::http::string_body> request,
+        boost::asio::yield_context yield,
+        std::chrono::steady_clock::duration timeout
+    );
+
+    std::expected<boost::beast::http::response<boost::beast::http::string_body>, boost::system::error_code>
+    receive(boost::asio::yield_context yield, std::chrono::steady_clock::duration timeout);
+
+    void
+    gracefulShutdown();
+    void
+    disconnect();
+};