Improve connection sharing demo (#362)

* Add a daemon socket listener so that the process loop will only execute if data is available on the socket.

* Set process loop timeout to 0 so that other commands do not have to wait for a process loop that isn't doing anything.

* Add an additional publisher task to show multiple tasks publishing simultaneously.

* Clarify what is meant by "synchronous" and "asynchronous" publishes.

* Fix possible race condition in task notification waits.

* Move task notification wait loop to its own function.

* The prvMQTTConnect function was doing more than just connecting, so it was split into more functions.

* Minor name changes for clarity.

* Add macros for AWS IoT metrics

FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/FreeRTOSIPConfig.h

@@ -227,7 +227,7 @@ extern UBaseType_t uxRand();
 #define ipconfigUSE_TCP                                ( 1 )
 
 /* Use the TCP socket wake context with a callback. */
-#define ipconfigSOCKET_HAS_USER_WAKE_CALLBACK_WITH_CONTEXT    ( 1 )
+#define ipconfigSOCKET_HAS_USER_WAKE_CALLBACK          ( 1 )
 
 /* USE_WIN: Let TCP use windowing mechanism. */
 #define ipconfigUSE_TCP_WIN                            ( 1 )

FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h

@@ -156,6 +156,70 @@
  */
 #define democonfigDISABLE_SNI    ( pdFALSE )
 
+/**
+ * @brief Configuration that indicates if the demo connection is made to the AWS IoT Core MQTT broker.
+ *
+ * If username/password based authentication is used, the demo will use appropriate TLS ALPN and
+ * SNI configurations as required for the Custom Authentication feature of AWS IoT.
+ * For more information, refer to the following documentation:
+ * https://docs.aws.amazon.com/iot/latest/developerguide/custom-auth.html#custom-auth-mqtt
+ *
+ * #define democonfigUSE_AWS_IOT_CORE_BROKER    ( 1 )
+ */
+
+/**
+ * @brief The username value for authenticating client to the MQTT broker when
+ * username/password based client authentication is used.
+ *
+ * For AWS IoT MQTT broker, refer to the AWS IoT documentation below for
+ * details regarding client authentication with a username and password.
+ * https://docs.aws.amazon.com/iot/latest/developerguide/custom-authentication.html
+ * An authorizer setup needs to be done, as mentioned in the above link, to use
+ * username/password based client authentication.
+ *
+ * #define democonfigCLIENT_USERNAME    "...insert here..."
+ */
+
+/**
+ * @brief The password value for authenticating client to the MQTT broker when
+ * username/password based client authentication is used.
+ *
+ * For AWS IoT MQTT broker, refer to the AWS IoT documentation below for
+ * details regarding client authentication with a username and password.
+ * https://docs.aws.amazon.com/iot/latest/developerguide/custom-authentication.html
+ * An authorizer setup needs to be done, as mentioned in the above link, to use
+ * username/password based client authentication.
+ *
+ * #define democonfigCLIENT_PASSWORD    "...insert here..."
+ */
+
+/**
+ * @brief The name of the operating system that the application is running on.
+ * The current value is given as an example. Please update for your specific
+ * operating system.
+ */
+#define democonfigOS_NAME                   "FreeRTOS"
+
+/**
+ * @brief The version of the operating system that the application is running
+ * on. The current value is given as an example. Please update for your specific
+ * operating system version.
+ */
+#define democonfigOS_VERSION                tskKERNEL_VERSION_NUMBER
+
+/**
+ * @brief The name of the hardware platform the application is running on. The
+ * current value is given as an example. Please update for your specific
+ * hardware platform.
+ */
+#define democonfigHARDWARE_PLATFORM_NAME    "WinSim"
+
+/**
+ * @brief The name of the MQTT library used and its version, following an "@"
+ * symbol.
+ */
+#define democonfigMQTT_LIB                  "core-mqtt@1.0.0"
+
 /**
  * @brief Whether to use mutual authentication. If this macro is not set to 1
  * or not defined, then plaintext TCP will be used instead of TLS over TCP.