[lake/iceberg] Support tier array type for iceberg

[XuQianJin-Stars]

Purpose

Linked issue: close #2252

This PR adds support for array type conversion between Fluss and Iceberg, enabling tiering of tables with array columns to Iceberg lakehouse storage.

Brief change log

• Updated FlussDataTypeToIcebergDataType to convert Fluss ARRAY type to Iceberg LIST type instead of throwing UnsupportedOperationException
• Created FlussArrayAsIcebergList adapter class to wrap Fluss InternalArray as Java List for Iceberg, supporting:
  • All primitive types (boolean, byte, short, int, long, float, double)
  • Complex types (string, char, decimal, timestamp, timestamp_ltz, date, time, binary, bytes)
  • Nested arrays (array of arrays)
  • Null handling for both array elements and null arrays
• Updated FlussRowAsIcebergRecord to handle array field conversion using the new adapter
• Enhanced IcebergConversions to support bidirectional type conversion (Iceberg LIST ↔ Fluss ARRAY)
• Updated documentation to include ARRAY → LIST in the Iceberg data type mapping table

Tests

Unit Tests (FlussRowAsIcebergRecordTest - 9 test cases):

• testArrayWithIntElements - Array of integers
• testArrayWithStringElements - Array of strings
• testNestedArrayType - Nested arrays (array of arrays)
• testArrayWithAllPrimitiveTypes - Arrays of all primitive types
• testArrayWithDecimalElements - Array of decimal values
• testArrayWithTimestampElements - Arrays of TIMESTAMP and TIMESTAMP_LTZ
• testArrayWithNullElements - Arrays with null elements
• testNullArray - Null array handling
• testArrayWithBinaryElements - Array of binary data

Integration Tests (IcebergTieringTest):

• testTieringWriteTableWithArrayType - Parameterized test (4 cases) covering:
  • Primary key tables with array columns (partitioned/non-partitioned)
  • Log tables with array columns (partitioned/non-partitioned)

Test Results: All 92 tests pass (increased from 88 tests before this PR)

API and Format

API Changes: None. No breaking changes to public APIs.

Storage Format: No changes to Fluss storage format. This only affects the conversion layer between Fluss and Iceberg during tiering operations.

Type Mapping:

• Fluss ARRAY<T> → Iceberg LIST<T> (element type T is converted recursively)
• Supports nullable and non-nullable arrays
• Maintains element type semantics through recursive conversion

Documentation

New Feature: Yes, this introduces array type support for Iceberg tiering.

Documentation Changes:

• Updated website/docs/streaming-lakehouse/integrate-data-lakes/iceberg.md
• Added ARRAY → LIST mapping to the data type compatibility table