[SPARK-20566][SQL] ColumnVector should support `appendFloats` for array

## What changes were proposed in this pull request?

This PR aims to add a missing `appendFloats` API for array into **ColumnVector** class. For double type, there is `appendDoubles` for array [here](https://github.com/apache/spark/blob/master/sql/core/src/main/java/org/apache/spark/sql/execution/vectorized/ColumnVector.java#L818-L824).

## How was this patch tested?

Pass the Jenkins with a newly added test case.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #17836 from dongjoon-hyun/SPARK-20566.