[SPARK-15776][SQL] Divide Expression inside Aggregation function is casted to wrong type

## What changes were proposed in this pull request?

This PR fixes the problem that Divide Expression inside Aggregation function is casted to wrong type, which cause `select 1/2` and `select sum(1/2)`returning different result.

**Before the change:**

```
scala> sql("select 1/2 as a").show()
+---+
|  a|
+---+
|0.5|
+---+

scala> sql("select sum(1/2) as a").show()
+---+
|  a|
+---+
|0  |
+---+

scala> sql("select sum(1 / 2) as a").schema
res4: org.apache.spark.sql.types.StructType = StructType(StructField(a,LongType,true))
```

**After the change:**

```
scala> sql("select 1/2 as a").show()
+---+
|  a|
+---+
|0.5|
+---+

scala> sql("select sum(1/2) as a").show()
+---+
|  a|
+---+
|0.5|
+---+

scala> sql("select sum(1/2) as a").schema
res4: org.apache.spark.sql.types.StructType = StructType(StructField(a,DoubleType,true))
```

## How was this patch tested?

Unit test.

This PR is based on https://github.com/apache/spark/pull/13524 by Sephiroth-Lin

Author: Sean Zhong <seanzhong@databricks.com>

Closes #13651 from clockfly/SPARK-15776.