[SPARK-17765][SQL] Support for writing out user-defined type in ORC datasource

## What changes were proposed in this pull request?

This PR adds the support for `UserDefinedType` when writing out instead of throwing `ClassCastException` in ORC data source.

In more details, `OrcStruct` is being created based on string from`DataType.catalogString`. For user-defined type, it seems it returns `sqlType.simpleString` for `catalogString` by default[1]. However, during type-dispatching to match the output with the schema, it tries to cast to, for example, `StructType`[2].

So, running the codes below (`MyDenseVector` was borrowed[3]) :

``` scala
val data = Seq((1, new UDT.MyDenseVector(Array(0.25, 2.25, 4.25))))
val udtDF = data.toDF("id", "vectors")
udtDF.write.orc("/tmp/test.orc")
```

ends up throwing an exception as below:

```
java.lang.ClassCastException: org.apache.spark.sql.UDT$MyDenseVectorUDT cannot be cast to org.apache.spark.sql.types.ArrayType
    at org.apache.spark.sql.hive.HiveInspectors$class.wrapperFor(HiveInspectors.scala:381)
    at org.apache.spark.sql.hive.orc.OrcSerializer.wrapperFor(OrcFileFormat.scala:164)
...
```

So, this PR uses `UserDefinedType.sqlType` during finding the correct converter when writing out in ORC data source.

[1]https://github.com/apache/spark/blob/dfdcab00c7b6200c22883baa3ebc5818be09556f/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala#L95
[2]https://github.com/apache/spark/blob/d2dc8c4a162834818190ffd82894522c524ca3e5/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala#L326
[3]https://github.com/apache/spark/blob/2bfed1a0c5be7d0718fd574a4dad90f4f6b44be7/sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala#L38-L70
## How was this patch tested?

Unit tests in `OrcQuerySuite`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15361 from HyukjinKwon/SPARK-17765.