ParquetDataset support configuration with default value #156
Description
User Story
The fixed-length features in TFRecord support configuration with default values（https://www.tensorflow.org/api_docs/python/tf/io/FixedLenFeature）, but currently, Parquet does not support this feature. If encountering a non-existent feature, an error will be thrown, such as 'No Column called xx found in yy'.
So when we transition from training with TFRecord to Parquet, there may be some functionality alignment issues. We hope that Parquet can also support configuration with default values.