fri: MQTT example with OTA capability

This example demonstrates how to develop cloud connected applications
and update them securely by integrating modular
FreeRTOS kernel(https://www.freertos.org/RTOS.html) and
libraries(https://www.freertos.org/libraries/categories.html) and
utilising hardware enforced security based on
Arm TrustZone Armv8-M(https://www.arm.com/architecture/learn-the-architecture/m-profile).
This example is based on
Corstone-300(https://developer.arm.com/Processors/Corstone-300

)
platform.

Signed-off-by: Devaraj Ranganna <devaraj.ranganna@arm.com>