Add handling of compiled schema in JSONUtils

:Release Notes:
Extended API for LSMessageJsonParser to handle already compiled JSON
schemas (i.e. pre-constructed).

:Detailed Notes:
Added ctor to take generic pbnjson::JSchema. Appropriate
pbnjson::JSchemaFragment was replaced with more generic version.

:Testing Performed:
Desktop build with https://g2g.palm.com/3596

:QA Notes:

:Issues Addressed:
[GF-40247] Support API to send XDS time to luna-sysservice
[GF-40249] Provide API to obtain EBT from luna-sysservice

Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Change-Id: I604394cb495b54ebef96d7bbcb56ae7dd15ea6e5
Reviewed-on: https://g2g.palm.com/3594
Reviewed-by: Sailesh Rachabathuni <sailesh.rachabathuni@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Tested-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Reviewed-by: Suresh Arumugam <suresh.arumugam@lge.com>
Tested-by: Suresh Arumugam <suresh.arumugam@lge.com>