feat(rt/posix): Added FreeRTOS-Plus-POSIX message queues implementation

Note: The current mq_open() implementation is changed to match
      the POSIX standard.

examples/system/rt_mqueue/CMakeLists.txt

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+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.16)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(posix_mqueue)

examples/system/rt_mqueue/README.md

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+| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C5 | ESP32-C6 | ESP32-H2 | ESP32-P4 | ESP32-S2 | ESP32-S3 |
+| ----------------- | ----- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- |
+
+# POSIX Message Queue Example
+
+A simple example using a POSIX message queue. Two tasks are reading from and writing to a POSIX message queue.
+
+## How to use example
+
+### Hardware Required
+
+This example should be able to run on any supported Espressif SoC development board.
+
+### Build and Flash
+
+Enter `idf.py -p PORT flash monitor` to build, flash and monitor the project.
+
+(To exit the serial monitor, type ``Ctrl-]``.)
+
+See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
+
+
+## Example Output
+
+If you see the following infinite console output, your example should be running correctly:
+
+```
+sending: 0
+received: 0
+sending: 1
+received: 1
+sending: 2
+received: 2
+sending: 3
+received: 3
+...
+```

examples/system/rt_mqueue/main/CMakeLists.txt

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+idf_component_register(SRCS "posix_mqueue_example_main.c"
+                    INCLUDE_DIRS "."
+                    PRIV_REQUIRES rt)

examples/system/rt_mqueue/main/posix_mqueue_example_main.c

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+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include <mqueue.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+
+static int s_counter = 0;
+
+const unsigned int MSG_PRIO = 0;
+
+static void *sender_function(void * arg)
+{
+    mqd_t *write_descr = (mqd_t*) arg;
+
+    while (true) {
+        printf("sending: %d\n", s_counter);
+        int result = mq_send(*write_descr, (const char*) &s_counter, sizeof(s_counter), MSG_PRIO);
+        if (result != 0) {
+            perror("Sending failed");
+            abort();
+        }
+
+        s_counter++;
+        sleep(1);
+    }
+
+    return NULL;
+}
+
+static void *receiver_function(void * arg)
+{
+    mqd_t *read_descr = (mqd_t*) arg;
+
+    while (true) {
+        int msg;
+        int result = mq_receive(*read_descr, (char*) &msg, sizeof(msg), NULL);
+        if (result == -1) {
+            perror("Sending failed");
+            abort();
+        }
+
+        printf("received: %d\n", msg);
+    }
+
+    return NULL;
+}
+
+void app_main(void)
+{
+    mqd_t write_descr;
+    mqd_t read_descr;
+    pthread_t sender;
+    pthread_t receiver;
+
+    struct mq_attr configuration = {
+        .mq_flags = 0, // ignored by mq_open
+        .mq_maxmsg = 10,
+        .mq_msgsize = sizeof(int),
+        .mq_curmsgs = 0 // ignored by mq_open
+    };
+
+    write_descr = mq_open("/my_queue", O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR , &configuration);
+    if (write_descr == (mqd_t) -1) {
+        perror("Creating message queue failed");
+        abort();
+    }
+
+    read_descr = mq_open("/my_queue", O_RDONLY);
+    if (read_descr == (mqd_t) -1) {
+        perror("Opening message queue for reading failed");
+        abort();
+    }
+
+    int result;
+    result = pthread_create(&sender, NULL, sender_function, &write_descr);
+    if (result != 0) {
+        printf("Creating sender thread failed: %s", strerror(errno));
+        abort();
+    }
+
+    result = pthread_create(&receiver, NULL, receiver_function, &read_descr);
+    if (result != 0) {
+        printf("Creating receiver thread failed: %s", strerror(errno));
+        abort();
+    }
+
+    while (true) {
+        sleep(1000);
+    }
+}

examples/system/rt_mqueue/pytest_rt_mqueue.py

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+# SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: CC0-1.0
+import pytest
+from pytest_embedded import Dut
+
+
+@pytest.mark.supported_targets
+@pytest.mark.generic
+def test_rt_mqueue_example(dut: Dut) -> None:
+    dut.expect_exact('sending: 0')
+    dut.expect_exact('received: 0')
+    dut.expect_exact('sending: 1')
+    dut.expect_exact('received: 1')