Providing insert json object string into kv-pair

:Release Notes:
Providing insert json object string into kv-pair

:Detailed Notes:
Introduce new API "PMLOGJSON(key, json_object_string)" to provide
insert json object string as a value.

:Testing Performed:
Compiled locally and tested on a device.

:QA Notes:

:Issues Addressed:
[GF-52565] Providing insert json object string into key-value pair

Open-webOS-DCO-1.0-Signed-off-by: Hongjeon Ha <hj.ha@lge.com>

Change-Id: I0f2fce1fb30e91175414ecabe19150298bf7f76a
Reviewed-on: https://g2g.palm.com/4020
Reviewed-by: DCO Verification
Reviewed-by: Hongjeon Ha <hj.ha@lge.com>
Tested-by: Hongjeon Ha <hj.ha@lge.com>
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>