Query/Json: implement optimized materializer for JSON queries with parameterless ctor

When JSON entity takes arguments in the ctor we need to do special processing - read all the JSON values into variables and only when we are done reading instantiate the entity and then do fixup. This is the scenario we currently have implemented since it's the most general-purpose. However, when entity doesn't have any ctor arguments we can instantiate it right away and do property/navigation hook-ups in place, saving some allocations.