[SPARK-12720][SQL] SQL Generation Support for Cube, Rollup, and Grouping Sets

#### What changes were proposed in this pull request?

This PR is for supporting SQL generation for cube, rollup and grouping sets.

For example, a query using rollup:
```SQL
SELECT count(*) as cnt, key % 5, grouping_id() FROM t1 GROUP BY key % 5 WITH ROLLUP
```
Original logical plan:
```
  Aggregate [(key#17L % cast(5 as bigint))#47L,grouping__id#46],
            [(count(1),mode=Complete,isDistinct=false) AS cnt#43L,
             (key#17L % cast(5 as bigint))#47L AS _c1#45L,
             grouping__id#46 AS _c2#44]
  +- Expand [List(key#17L, value#18, (key#17L % cast(5 as bigint))#47L, 0),
             List(key#17L, value#18, null, 1)],
            [key#17L,value#18,(key#17L % cast(5 as bigint))#47L,grouping__id#46]
     +- Project [key#17L,
                 value#18,
                 (key#17L % cast(5 as bigint)) AS (key#17L % cast(5 as bigint))#47L]
        +- Subquery t1
           +- Relation[key#17L,value#18] ParquetRelation
```
Converted SQL:
```SQL
  SELECT count( 1) AS `cnt`,
         (`t1`.`key` % CAST(5 AS BIGINT)),
         grouping_id() AS `_c2`
  FROM `default`.`t1`
  GROUP BY (`t1`.`key` % CAST(5 AS BIGINT))
  GROUPING SETS (((`t1`.`key` % CAST(5 AS BIGINT))), ())
```

#### How was the this patch tested?

Added eight test cases in `LogicalPlanToSQLSuite`.

Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>

Closes #11283 from gatorsmile/groupingSetsToSQL.

0 files changed, 0 insertions, 0 deletions