[GLUTEN-12459][FLINK] feat: supprt RowKind via $row_kind TINYINT column between Flink and Velox

[ggjh-159]

Related issue: #12459

What changes are proposed in this pull request?

Flink RowData carries a RowKind header (+I / -U / +U / -D, byte ordinals 0/1/2/3) that today is lost the moment a row is converted to a velox RowVector. As a result every row exiting the velox pipeline is stamped +I, retract sinks print wrong prefixes, and any future retract-aware operator loses its input signal.

This PR threads RowKind through the conversion layer as a trailing TINYINT column named $row_kind, matching the convention already used on the velox side (kRowKindColumnName in velox/experimental/stateful/RowKind.h, ChangelogRowVector::toMergedRowVector). The user-visible schema is unchanged; the extra column is appended/stripped at the Flink boundary.

Changes:

• ArrowVectorWriter: add TinyIntVectorWriter + TINYINT → ArrowType.Int(8, true) mapping so TINYINT columns can be written from RowData.getByte(...).
• ArrowVectorAccessor: add TinyIntVectorAccessor so TINYINT columns can be read back as byte.
• FlinkRowToVLVectorConvertor:
  • fromRowData now appends a single-row $row_kind TINYINT vector populated from row.getRowKind().toByteValue().
  • toRowData reads only rowType.size() user fields, then looks at the trailing column. If it is the $row_kind TINYINT vector, each row is reconstructed with GenericRowData.ofKind(...); otherwise the previous GenericRowData.of(...) path is taken (INSERT only), preserving backwards compatibility with append-only streams that never carry the column.

How was this patch tested?

• UTs
• E2E test, nexmark stateless sql

Depends on the velox4j(bigo-sg/velox4j#57).