## What changes were proposed in this pull request?
Refactor `DatasetBenchmark` to use main method.
Generate benchmark result:
```sh
SPARK_GENERATE_BENCHMARK_FILES=1 build/sbt "sql/test:runMain org.apache.spark.sql.DatasetBenchmark"
```
## How was this patch tested?
manual tests
Closes#22488 from wangyum/SPARK-25479.
Lead-authored-by: Yuming Wang <yumwang@ebay.com>
Co-authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
