[SPARK-15280] Input/Output] Refactored OrcOutputWriter and moved serialization to a new class.

## What changes were proposed in this pull request?
Refactoring: Separated ORC serialization logic from OrcOutputWriter and moved to a new class called OrcSerializer.

## How was this patch tested?
Manual tests & existing tests.

Author: Ergin Seyfe <eseyfe@fb.com>

Closes #13066 from seyfe/orc_serializer.