Extended API to the ID generation logic

:Release Notes:
Extended API to the ID generation logic. Now we can extract shardId from
_id.

:Detailed Notes:
- add method for generation _id with shardId specified as a MojUInt32
- add method for extracting shard from _id (required for GF-9286)
- added more unit-tests for MojDbIdGenerator class to test logic of new
  and some old calls

:Testing Performed:
unit-tests included in this commit

:QA Notes:

:Issues Addressed:

Open-webOS-DCO-1.0-Signed-off-by: Nikolay Orliuk <nikolay.orliuk@lge.com>
Change-Id: I09e15620adff05f91f073ff674d84c17055f827e
Reviewed-on: https://g2g.palm.com/3177
Reviewed-by: Build Verification
Reviewed-by: Roger Stringer <roger.stringer@lge.com>
Tested-by: Roger Stringer <roger.stringer@lge.com>