[VL][Delta] Add UniForm Iceberg support wiring

[malinjawi]

What changes are proposed in this pull request?

This PR adds the first Velox Delta write-side support slice for UniForm Iceberg.

The change keeps Delta as the source of truth for the transaction and UniForm metadata-generation flow. Gluten now passes Delta column-mapping field IDs through the Velox native Parquet writer path when IcebergCompatV2 is enabled, so newly written Delta files can satisfy the Parquet field-id part of the UniForm Iceberg contract.

This PR also:

• adds delta-iceberg to the Velox Delta build/test profile
• serializes Delta column-mapping field IDs into native Parquet writer options
• parses that option on the Velox side and populates WriterOptions.parquetFieldIds
• preserves the existing Delta async UniForm metadata generation path after commit
• adds a focused end-to-end UniForm Iceberg suite with Hive Metastore-backed Iceberg readback
• adds negative coverage for active deletion vectors
• updates docs/get-started/VeloxDelta.md from Not tested to Partial

Current scope / behavior:

• Spark 3.5 Velox native Delta write is covered for new UniForm Iceberg tables using IcebergCompatV2
• the test verifies generated Iceberg metadata and reads the table back through Iceberg
• active deletion vectors are rejected by Delta for UniForm Iceberg
• native Velox Iceberg scan for UniForm column-mapping/name-mapping reads is still a follow-up gap, so the docs do not claim full native read support yet

How was this patch tested?

Build / validation:

• ./build/mvn -Pbackends-velox,delta,spark-3.5 -pl backends-velox -am -DskipTests test-compile
• ninja -j 6 gluten
• ninja -j 6 libvelox.dylib
• git diff --check

Focused local validation:

• Spark 3.5 org.apache.spark.sql.delta.DeltaUniFormIcebergSuite with -Pbackends-velox,delta,iceberg,spark-3.5
• Spark 3.5 org.apache.spark.sql.delta.DeltaUniFormIcebergSuite with -Pbackends-velox,delta,spark-3.5 to verify clean cancellation without Iceberg test classes
• Spark 3.5 org.apache.spark.sql.delta.DeltaInsertIntoSQLNameColumnMappingSuite

Functional validation:

• verified a UniForm Iceberg-enabled Delta table can be written through the Velox native Delta write path
• verified Parquet files are written with IcebergCompatV2-compatible field IDs
• verified Iceberg metadata JSON is generated after commit
• verified generated metadata contains Delta version/timestamp information
• verified the table can be read back through Iceberg with expected rows
• verified active deletion vectors are rejected for UniForm Iceberg

Was this patch authored or co-authored using generative AI tooling?

Generated-by: IBM BOB

issue: #12039

Follow-up work

This PR intentionally keeps the scope limited to the supported Delta write and Iceberg readback path. Reasonable follow-ups are:

• add native Velox Iceberg read support for UniForm column-mapping/name-mapping tables by plumbing Iceberg/Parquet field IDs through the scan path
• add Spark 4.0 UniForm coverage if the same Delta/Iceberg dependency set is enabled there
• broaden negative coverage for upgrade/rewrite paths that require REORG TABLE ... APPLY (UPGRADE UNIFORM(...))
• tighten docs once native Iceberg scan support is proven

[github-actions]

Run Gluten Clickhouse CI on x86

[github-actions]

Run Gluten Clickhouse CI on x86

[github-actions]

Run Gluten Clickhouse CI on x86

[github-actions]

Run Gluten Clickhouse CI on x86