upsert method
Implementation
Future<RowData?> upsert(Object table, {required Iterable<ColumnValue> values, required Iterable<Object> constraints, Returning? returning}) async {
assert(values.isNotEmpty);
return await upsertValues(table, columns: values.map((e) => e.key), constraints: constraints, values: values.map((e) => e.value), returning: returning);
}