### What changes were proposed in this pull request?
unionByName does not supports struct having same col names but different sequence
```
val df1 = Seq((1, Struct1(1, 2))).toDF("a", "b")
val df2 = Seq((1, Struct2(1, 2))).toDF("a", "b")
val unionDF = df1.unionByName(df2)
```
it gives the exception
`org.apache.spark.sql.AnalysisException: Union can only be performed on tables with the compatible column types. struct<c2:int,c1:int> <> struct<c1:int,c2:int> at the second column of the second table; 'Union false, false :- LocalRelation [_1#38, _2#39] +- LocalRelation _1#45, _2#46`
In this case the col names are same so this unionByName should have the support to check within in the Struct if col names are same it should not throw this exception and works.
after fix we are getting the result
```
val unionDF = df1.unionByName(df2)
scala> unionDF.show
+---+------+
| a| b|
+---+------+
| 1|{1, 2}|
| 1|{2, 1}|
+---+------+
```
### Why are the changes needed?
As per unionByName functionality based on name, does the union. In the case of struct this scenario was missing where all the columns names are same but sequence is different, so added this functionality.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Added the unit test and also done the testing through spark shell
Closes#32972 from SaurabhChawla100/SPARK-35756.
Authored-by: SaurabhChawla <s.saurabhtim@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
ca1217667c