Add extracted tools: CitrineOS, OpenOCPP, ShapeShifter

- CitrineOS core extracted (CSMS OCPP 2.0.1)
- OpenOCPP extracted (firmware OCPP 1.6J/2.0.1)
- ShapeShifter library installed (pip install -e)
- ShapeShifter specification extracted
- EVerest extracted

TODO updated with progress

tools/EVerest-main/lib/everest/io/examples/test_mosquitto_client.cpp

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 - 2025 Pionix GmbH and Contributors to EVerest
+
+/**
+ * @example test_mqtt_client.cpp Creates two MQTT clients that ping/pong messages to each other
+ */
+
+#include "everest/io/mqtt/mosquitto_cpp.hpp"
+#include <cstdio>
+#include <everest/io/event/fd_event_handler.hpp>
+#include <everest/io/event/timer_fd.hpp>
+#include <everest/io/mqtt/mqtt_client.hpp>
+#include <iostream>
+#include <string>
+#include <thread>
+
+using namespace everest::lib::io::event;
+using namespace everest::lib::io;
+using namespace std::chrono_literals;
+
+constexpr auto HOST = "localhost";
+constexpr std::uint16_t PORT = 1883;
+
+using payloadT = mqtt::mosquitto_cpp::message;
+using generic_client = typename mqtt::mosquitto_cpp;
+
+// Creates the error handler for the clients
+mqtt::mqtt_client::cb_error make_error_cb(mqtt::mqtt_client& client) {
+    return [&](int error, std::string const& msg) {
+        std::cerr << "ERROR ( " << error << " ): " << msg << std::endl;
+        if (error) {
+            std::cout << "What to do?" << std::endl;
+        }
+    };
+}
+
+// Creates the RX handler for the client
+mqtt::mqtt_client::subscribe_message_callback make_rx_callback(mqtt::mosquitto_cpp&, std::string tar) {
+    return [&, tar](generic_client& client, payloadT const& data) {
+        std::cout << &client << "\n"
+                  << "topic: " << data.topic << "\n"
+                  << "msg:   " << data.payload << std::endl;
+        payloadT dataset;
+        auto c = std::stoi(data.payload) + 1;
+        dataset.payload = std::to_string(c);
+        dataset.topic = tar;
+        client.publish(dataset);
+    };
+}
+
+int main(int, char*[]) {
+    std::cout << "mqtt_client ping/pong demonstration" << std::endl;
+    bool server_connected = false;
+    bool client_connected = false;
+
+    // Create first mqtt_client
+    mqtt::mqtt_client client(2000);
+    // Create and assign error handler
+    client.set_error_handler(make_error_cb(client));
+    // Create and assign rx handler
+    client.set_callback_connect([&](auto& mqtt, auto, auto, auto const&) {
+        client_connected = true;
+        mqtt.subscribe("test/client/recv/#", make_rx_callback(mqtt, "test/server/recv"),
+                       mqtt::mosquitto_cpp::QoS::at_most_once);
+        if (server_connected) {
+            mqtt.publish("test/server/recv", "1");
+        }
+    });
+    client.connect(HOST, PORT, 1000);
+
+    // Create second mqtt_client
+    mqtt::mqtt_client server(2000);
+    server.set_callback_connect([&](auto& mqtt, auto, auto, auto const&) {
+        server_connected = true;
+        mqtt.subscribe("test/server/recv/#", make_rx_callback(mqtt, "test/client/recv"),
+                       mqtt::mosquitto_cpp::QoS::at_most_once);
+        if (client_connected) {
+            mqtt.publish("test/client/recv", "1");
+        }
+    });
+    server.set_error_handler(make_error_cb(server));
+
+    server.connect(HOST, PORT, 1000);
+
+    // Create event handler and register clients
+    fd_event_handler ev_handler;
+    ev_handler.register_event_handler(&client);
+    ev_handler.register_event_handler(&server);
+
+    std::atomic_bool running = true;
+    ev_handler.run(running);
+
+    return 0;
+}