[PR from CLI tool] Fix pointer logging warnings in MQTT library

[aggarw13]

Fix build warnings with -Wall -Wextra flags for pointer logging in MQTT files.

Description of changes:

• Use (void *) cast for logging non-function pointers
• Remove logging of function pointers as ISO C does not support (void *) cast of function pointers (Only POSIX does)

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

[codecov-commenter]

Codecov Report

Merging #1109 into development will increase coverage by 1.91%.
The diff coverage is 81.48%.

@@               Coverage Diff               @@
##           development    #1109      +/-   ##
===============================================
+ Coverage        96.54%   98.46%   +1.91%     
===============================================
  Files                9        4       -5     
  Lines             5643     1301    -4342     
  Branches           641      385     -256     
===============================================
- Hits              5448     1281    -4167     
+ Misses               9        0       -9     
+ Partials           186       20     -166     

Impacted Files	Coverage Δ
libraries/standard/mqtt/src/mqtt.c	99.46% <ø> (+5.05%)	⬆️
libraries/standard/mqtt/src/mqtt_lightweight.c	97.44% <ø> (+2.92%)	⬆️
libraries/standard/mqtt/src/mqtt_state.c	98.46% <ø> (+2.52%)	⬆️
libraries/standard/http/src/http_client.c	98.53% <81.48%> (+11.05%)	⬆️

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[muneebahmed10]

What's the purpose in separating these parameters? It seems more repetitive this way, and it doesn't match the condition earlier in this function, at line 1374

[aggarw13]

The earlier implementation was printing the function pointers under a single if condition so that the reader could detect which of the function pointers is null. However, casting function pointers to void * for printing is not supported by ISO C.
GCC gives the following warning when casting function pointers to void *

/home/ubuntu/Repos/aws-iot-device-sdk-embedded-C/libraries/standard/mqtt/src/mqtt.c:1387:21: warning: format ‘%p’ expects argument of type ‘void *’, but argument 2 has type ‘MQTTGetCurrentTimeFunc_t {aka unsigned int (*)(void)}’ [-Wformat=]
         LogError( ( "Invalid parameter: getTimeFunction is NULL: %p", getTimeFunction ) );
                     ^
/home/ubuntu/Repos/aws-iot-device-sdk-embedded-C/demos/logging-stack/logging_stack.h:49:40: note: in definition of macro ‘SdkLog’
     #define SdkLog( string )    printf string
                                        ^~~~~~
/home/ubuntu/Repos/aws-iot-device-sdk-embedded-C/libraries/standard/mqtt/src/mqtt.c:1387:9: note: in expansion of macro ‘LogError’
         LogError( ( "Invalid parameter: getTimeFunction is NULL: %p", getTimeFunction ) );