Azure iothub direct method support

[PabasaraDilshan]

Description:

Azure iothub direct method feature support to receive messages to device via direct method and send response. Direct method feature can be added with adding this code snippet to user_config_override_sample.h

#ifndef USE_MQTT_TLS
#define USE_MQTT_TLS
#endif
#define USE_MQTT_AZURE_IOT
#define USE_AZURE_DIRECT_METHOD

Also required to enable MQTT_TLS_ENABLED and SetOption132 1 to establish connection with azure iot hub.

Example:
Method:

POWER

Payload:

{
"payload":"ON"
}

https://learn.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-direct-methods

Related issue (if applicable): fixes #

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.6
• The code change is tested and works with Tasmota core ESP32 V.2.0.14
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[s-hadinger]

No!!! data_len is the size of mqtt_data and is used to avoid buffer overflow. Changing data_len to the length of an arbitrary string received on the wire is wrong.

Remove this line.

strncpy copies the string with no more than data_len bytes, it figures out on its own the size of the source string.

[s-hadinger]

Overall I'm ok except the buffer_overflow vulnerability accidentally introduced. Please fix so we can merge.

[s-hadinger]

I di the change myself and merged