[SPARK-19471][SQL]AggregationIterator does not initialize the generated result projection before using it

[DonnyZone]

What changes were proposed in this pull request?

Recently, we have also encountered such NPE issues in our production environment as introduced in:
https://issues.apache.org/jira/browse/SPARK-19471

This issue can be reproduced by the following examples:

` val df = spark.createDataFrame(Seq(("1", 1), ("1", 2), ("2", 3), ("2", 4))).toDF("x", "y")

//HashAggregate, SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key=false
df.groupBy("x").agg(rand(),sum("y")).show()

//ObjectHashAggregate, SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key=false
df.groupBy("x").agg(rand(),collect_list("y")).show()

//SortAggregate, SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key=false &&SQLConf.USE_OBJECT_HASH_AGG.key=false
df.groupBy("x").agg(rand(),collect_list("y")).show()`

This PR is based on PR-16820(#16820) with test cases for all aggregation paths.

When AggregationIterator generates result projection, it does not call the initialize method of the Projection class. This will cause a runtime NullPointerException when the projection involves nondeterministic expressions.

How was this patch tested?

unit test

[DonnyZone]

There are some confilicts, close it first