[SPARK-40292][SQL] Fix column names in "arrays_zip" function when arr…

…ays are referenced from nested structs

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

This PR fixes an issue in `arrays_zip` function where a field index was used as a column name in the resulting schema which was a regression from Spark 3.1. With this change, the original behaviour is restored: a corresponding struct field name will be used instead of a field index.

Example:
```sql
with q as (
  select
    named_struct(
      'my_array', array(1, 2, 3),
      'my_array2', array(4, 5, 6)
    ) as my_struct
)
select
  arrays_zip(my_struct.my_array, my_struct.my_array2)
from
  q
```

would return schema:
```
root
 |-- arrays_zip(my_struct.my_array, my_struct.my_array2): array (nullable = false)
 |    |-- element: struct (containsNull = false)
 |    |    |-- 0: integer (nullable = true)
 |    |    |-- 1: integer (nullable = true)
```

which is somewhat inaccurate. PR adds handling of `GetStructField` expression to return the struct field names like this:
```
root
 |-- arrays_zip(my_struct.my_array, my_struct.my_array2): array (nullable = false)
 |    |-- element: struct (containsNull = false)
 |    |    |-- my_array: integer (nullable = true)
 |    |    |-- my_array2: integer (nullable = true)
```

### Why are the changes needed?

### Does this PR introduce _any_ user-facing change?

Yes, `arrays_zip` function returns struct field names now as in Spark 3.1 instead of field indices.
Some users might have worked around this issue so this patch would affect them by bringing back the original behaviour.

### How was this patch tested?

Existing unit tests. I also added a test case that reproduces the problem.

Closes apache#37833 from sadikovi/SPARK-40292.

Authored-by: Ivan Sadikov <ivan.sadikov@databricks.com>
Signed-off-by: Max Gekk <max.gekk@gmail.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala

@@ -270,6 +270,7 @@ case class ArraysZip(children: Seq[Expression], names: Seq[Expression])
         case (u: UnresolvedAttribute, _) => Literal(u.nameParts.last)
         case (e: NamedExpression, _) if e.resolved => Literal(e.name)
         case (e: NamedExpression, _) => NamePlaceholder
+        case (e: GetStructField, _) => Literal(e.extractFieldName)
         case (_, idx) => Literal(idx.toString)
       })
   }

sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala

@@ -763,6 +763,25 @@ class DataFrameFunctionsSuite extends QueryTest with SharedSparkSession {
     }
   }
 
+  test("SPARK-40292: arrays_zip should retain field names in nested structs") {
+    val df = spark.sql("""
+      select
+        named_struct(
+          'arr_1', array(named_struct('a', 1, 'b', 2)),
+          'arr_2', array(named_struct('p', 1, 'q', 2)),
+          'field', named_struct(
+            'arr_3', array(named_struct('x', 1, 'y', 2))
+          )
+        ) as obj
+      """)
+
+    val res = df.selectExpr("arrays_zip(obj.arr_1, obj.arr_2, obj.field.arr_3) as arr")
+
+    val fieldNames = res.schema.head.dataType.asInstanceOf[ArrayType]
+      .elementType.asInstanceOf[StructType].fieldNames
+    assert(fieldNames.toSeq === Seq("arr_1", "arr_2", "arr_3"))
+  }
+
   def testSizeOfMap(sizeOfNull: Any): Unit = {
     val df = Seq(
       (Map[Int, Int](1 -> 1, 2 -> 2), "x"),