feat: implement basic parquet writer and add roundtrip tests

[HuaHuaY]

Add parquet writer factory and basic parquet writer without metrics.

[Copilot]

Pull Request Overview

This PR implements a basic ParquetWriter class for writing ArrowArray data to Parquet files. The implementation follows the Writer interface pattern and uses Apache Arrow/Parquet libraries for the underlying functionality.

• Adds ParquetWriter class with PIMPL pattern for encapsulation
• Implements core writer operations: Open, Write, Close with Arrow/Parquet integration
• Provides placeholder implementations for metrics, length, and split_offsets methods

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/iceberg/parquet/parquet_writer.h	Header file defining the ParquetWriter class interface with PIMPL pattern
src/iceberg/parquet/parquet_writer.cc	Implementation of ParquetWriter with Arrow/Parquet integration and factory registration
src/iceberg/CMakeLists.txt	Adds parquet_writer.cc to the build configuration

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[wgtmac]

LGTM. Left some nits.