Function parse_json 

pub fn parse_json(
    json_strings: Box<dyn EngineData>,
    schema: Arc<StructType>,
) -> Result<Box<dyn EngineData>, Error>

Arrow lacks the functionality to json-parse a string column into a struct column, so we implement it here. This method is for json-parsing each string in a column of strings (add.stats to be specific) to produce a nested column of strongly typed values. We require that N rows in means N rows out.