## What changes were proposed in this pull request?
Union of map and other compatible column result in unresolved operator 'Union; exception
Reproduction
`spark-sql>select map(1,2), 'str' union all select map(1,2,3,null), 1`
Output:
```
Error in query: unresolved operator 'Union;;
'Union
:- Project [map(1, 2) AS map(1, 2)#106, str AS str#107]
: +- OneRowRelation$
+- Project [map(1, cast(2 as int), 3, cast(null as int)) AS map(1, CAST(2 AS INT), 3, CAST(NULL AS INT))#109, 1 AS 1#108]
+- OneRowRelation$
```
So, we should cast part of columns to be compatible when appropriate.
## How was this patch tested?
Added a test (query union of map and other columns) to SQLQueryTestSuite's union.sql.
Author: liutang123 <liutang123@yeah.net>
Closes#21100 from liutang123/SPARK-24012.
64e8408e6f