factor out LSCategoryMethodCall

:Release Notes:

:Detailed Notes:
- extracted LSCategoryMethodCall from _LSHandleMethodCall

:Testing Performed:
unit-tests on desktop

:QA Notes:

:Issues Addressed:
[BHV-4021] Re-factor LS2 to keep its own copy of LSMethod info

Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <nikolay.orliuk@lge.com>

Change-Id: Ib702e652991b508e8ffc6ea2381be3b9fadc4c17
Reviewed-on: https://g2g.palm.com/5219
Reviewed-by: DCO Verification
Reviewed-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Tested-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Reviewed-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>