[SPARK-22881][ML][TEST] ML regression package testsuite add StructuredStreaming test

## What changes were proposed in this pull request?

ML regression package testsuite add StructuredStreaming test

In order to make testsuite easier to modify, new helper function added in `MLTest`:
```
def testTransformerByGlobalCheckFunc[A : Encoder](
      dataframe: DataFrame,
      transformer: Transformer,
      firstResultCol: String,
      otherResultCols: String*)
      (globalCheckFunction: Seq[Row] => Unit): Unit
```

## How was this patch tested?

N/A

Author: WeichenXu <weichen.xu@databricks.com>
Author: Bago Amirbekian <bago@databricks.com>

Closes #19979 from WeichenXu123/ml_stream_test.