Step 1 towards a correct JSON payload rendering

### Description
Started with UpdateContextAvailabilitySubscriptionRequest::render and it just grew and grew ...
- Added parameter 'bool comma' in quite a few render methods - necessary for JSON rendering.
- Restriction counting no longer in the ParseData structures, but in the very payload structure.
    And ... the restriction counting had many failures, now fixed. Not all are fixed, but quite a few.
- Made many xxxInit parse functions more homogenous.
- Renamed reqData to reqDataP in xmlSubscribeContextAvailabilityRequest.cpp, sorry ...