### What changes were proposed in this pull request?
add a new method `def test(dataset: DataFrame, featuresCol: String, labelCol: String, flatten: Boolean): DataFrame`
### Why are the changes needed?
Similar to new `test` method in `ChiSquareTest`, it will:
1, support df operation on the returned df;
2, make driver no longer a bottleneck with large numFeatures
### Does this PR introduce any user-facing change?
Yes, new method added
### How was this patch tested?
existing testsuites
Closes#28270 from zhengruifeng/flatten_anova.
Authored-by: zhengruifeng <ruifengz@foxmail.com>
Signed-off-by: zhengruifeng <ruifengz@foxmail.com>
e7bc6f38b9