STM32F767ZI: Implement MQTT Telemetry and Finalize Network Station Demo

[alieissa-commits]

Description

Complete the environmental station by adding cloud connectivity and wiring all the application threads together.

• Integrate the NetX Duo MQTT client module.
• Create a ThreadX network_thread to connect to a remote MQTT broker.
• Format the sensor data (e.g., as JSON) and publish it to the relevant MQTT topics.
• Finalize the demo by ensuring all threads (sensor, logger, network, and status LEDs) cooperate smoothly.