Function csv_str_to_cql_value 

pub fn csv_str_to_cql_value(
    field: &str,
    type_name: &str,
    null_val: &str,
) -> Result<CqlValue>

Convert a CSV string field to a typed CqlValue based on the CQL column type.

type_name is the raw CQL type string from system_schema.columns.type (e.g. "int", "text", "list<int>", "frozen<set<uuid>>"). Complex nested types (list, set, map, tuple, frozen, udt) are preserved as CqlValue::Text literals — the database will parse them via the unprepared path.