Introduce PmLogMsg() key value pair API

Introduce PmLogMsg() API and related convenience macros:
  - PmLogCritical()
  - PmLogError()
  - PmLogWarning()
  - PmLogInfo()
  - PmLogDebug()
  - PMLOGKFV()
  - PMLOGKS()

Following new field is introduced with the new API:
  - msgid    : Unique id for a message within a context

Special thanks to Herb Kuta for suggesting a brilliant design and providing
a python script for generating macros!

[GF-2753] pmloglib: Organize message format

Open-webOS-DCO-1.0-Signed-off-by: Ameya Palande <ameya.palande@lge.com>
Open-webOS-DCO-1.0-Signed-off-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>

Change-Id: Ibe2ea47e753b9689c4fda07ef6f308b714022cfd