The keyword and speech apps can now use the NetX Duo Azure IoT
Middleware for Azure RTOS addon to connect to Azure using ThreadX
and the NetX Duo networking stack.

Some Azure ceritification and device connection files have been imported
from NetX Duo Azure IOT sample example. These are:
* bsp/netxduo-config/nx_azure_iot_cert.c
* bsp/netxduo-config/nx_azure_iot_cert.h
* bsp/netxduo-config/nx_azure_iot_ciphersuites.c
* bsp/netxduo-config/nx_azure_iot_ciphersuites.h
* bsp/netxduo-config/sample_azure_iot_embedded_sdk_connect.c

Signed-off-by: Hugues Kamba-Mpiana <hugues.kambampiana@arm.com>