[Kernel] Remove the protocol specific conversions from `JsonHandler.parseJSON`

[vkorukanti]

Feature request

Currently the JsonHandler.parseJson parses the stats values. Some of these values are for columns of type TIMESTAMP, DATE which are not native types in Json. Exactly how the string format of the TIMESTAMP, DATE can be interpreted depends on the Delta protocol details. We want to change it as follows:

1. JsonHandler.parseJson just parses as native json types
2. Kernel-API module applies expressions on the parsed JSON values to convert them to appropriate types.