[FEA] read_json should output all-nulls columns for the schema columns that do not exist in the input

[ttnghia]

In order to fulfill some applications such as Spark, read_json needs to output all-nulls columns for the columns in the input schema that do not exist in the input data. This applies to all schema columns at any nested level.

If there is conflict of interest between applications, we can implement this as a reader option.