feat: [presto][iceberg] Add Variant type support for Iceberg V3 (prestodb#27374)

Summary:
Pull Request resolved: prestodb#27374

== RELEASE NOTES ==

General Changes
* Upgrade Apache Iceberg library from 1.10.0 to 1.10.1.

Hive Connector Changes
* Add Iceberg V3 deletion vector (DV) support using Puffin-encoded roaring
  bitmaps, including a DV reader, writer, page sink, and compaction procedure.
* Add Iceberg equality delete file reader with sequence number conflict
  resolution per the Iceberg V2+ spec: equality deletes skip when
  deleteFileSeqNum <= dataFileSeqNum; positional deletes and DVs skip when
  deleteFileSeqNum < dataFileSeqNum; sequence number 0 (V1 legacy) never skips.
* Wire dataSequenceNumber through the Presto protocol layer (Java → C++)
  to enable server-side sequence number conflict resolution for all delete
  file types.
* Add PUFFIN file format support for deletion vector discovery, enabling
  the coordinator to locate DV files during split creation.
* Add Iceberg V3 deletion vector write path with DV page sink and
  rewrite_delete_files compaction procedure for DV maintenance.
* Add nanosecond timestamp (TIMESTAMP_NANO) type support for Iceberg V3
  tables.
* Add Variant type support for Iceberg V3, enabling semi-structured data
  columns in Iceberg tables.
* Eagerly collect delete files during split creation with improved logging
  for easier debugging of Iceberg delete file resolution.
* Improve IcebergSplitReader error handling and fix test file handle leaks.
* Add end-to-end integration tests for Iceberg V3 covering snapshot
  lifecycle (INSERT, DELETE with equality/positional/DV deletes, UPDATE,
  MERGE, time-travel) and all 99 TPC-DS queries.

Add support for Iceberg V3 VARIANT type across the Presto-Iceberg connector type
conversion pipeline. The VARIANT type represents semi-structured data (JSON) and is
mapped to Presto's unbounded VARCHAR type.

Changes:
- TypeConverter: Map VARIANT to VarcharType (unbounded) in toPrestoType(), and to
  ORC STRING type in toOrcType()
- IcebergUtil: Handle VARIANT partition values as string slices in domain creation
- PartitionData: Deserialize VARIANT partition values as text (same as STRING)
- PartitionTable: Convert VariantType partition values to string representation
- TestIcebergV3: Add comprehensive e2e tests for VARIANT type

The VARIANT type in Iceberg 1.10.0 implements Type directly (not PrimitiveType or
NestedType), so ColumnIdentity handling works automatically via the existing
!isNestedType() check.

Differential Revision: D96755027

Author: apurva-meta

presto-iceberg/src/main/java/com/facebook/presto/iceberg/IcebergConnector.java

@@ -16,6 +16,7 @@
 import com.facebook.airlift.bootstrap.LifeCycleManager;
 import com.facebook.presto.hive.HiveTransactionHandle;
 import com.facebook.presto.iceberg.function.IcebergBucketFunction;
+import com.facebook.presto.iceberg.function.VariantFunctions;
 import com.facebook.presto.iceberg.function.changelog.ApplyChangelogFunction;
 import com.facebook.presto.iceberg.transaction.IcebergTransactionManager;
 import com.facebook.presto.iceberg.transaction.IcebergTransactionMetadata;
@@ -256,6 +257,7 @@ public Set<Class<?>> getSystemFunctions()
                 .add(ApplyChangelogFunction.class)
                 .add(IcebergBucketFunction.class)
                 .add(IcebergBucketFunction.Bucket.class)
+                .add(VariantFunctions.class)
                 .build();
     }
 

presto-iceberg/src/main/java/com/facebook/presto/iceberg/IcebergUtil.java

@@ -782,6 +782,7 @@ public static Domain createDomainFromIcebergPartitionValue(
             case TIMESTAMP_NANO:
                 return singleValue(prestoType, Math.floorDiv((Long) value, 1000L));
             case STRING:
+            case VARIANT:
                 return singleValue(prestoType, utf8Slice(value.toString()));
             case FLOAT:
                 return singleValue(prestoType, (long) floatToRawIntBits((Float) value));

presto-iceberg/src/main/java/com/facebook/presto/iceberg/PartitionData.java

@@ -176,6 +176,7 @@ public static Object getValue(JsonNode partitionValue, Type type)
                 }
                 return partitionValue.doubleValue();
             case STRING:
+            case VARIANT:
                 return partitionValue.asText();
             case FIXED:
             case BINARY:

presto-iceberg/src/main/java/com/facebook/presto/iceberg/PartitionTable.java

@@ -287,7 +287,7 @@ private Object convert(Object value, Type type)
         if (value == null) {
             return null;
         }
-        if (type instanceof Types.StringType) {
+        if (type instanceof Types.StringType || type.isVariantType()) {
             return value.toString();
         }
         if (type instanceof Types.BinaryType) {

presto-iceberg/src/main/java/com/facebook/presto/iceberg/TypeConverter.java

@@ -147,6 +147,8 @@ public static Type toPrestoType(org.apache.iceberg.types.Type type, TypeManager
                 return RowType.from(fields.stream()
                         .map(field -> new RowType.Field(Optional.of(field.name()), toPrestoType(field.type(), typeManager)))
                         .collect(toImmutableList()));
+            case VARIANT:
+                return VarcharType.createUnboundedVarcharType();
             default:
                 throw new UnsupportedOperationException(format("Cannot convert from Iceberg type '%s' (%s) to Presto type", type, type.typeId()));
         }
@@ -411,6 +413,7 @@ private static List<OrcType> toOrcType(int nextFieldTypeIndex, org.apache.iceber
             case TIMESTAMP_NANO:
                 return ImmutableList.of(new OrcType(OrcType.OrcTypeKind.TIMESTAMP, ImmutableList.of(), ImmutableList.of(), Optional.empty(), Optional.empty(), Optional.empty(), attributes));
             case STRING:
+            case VARIANT:
                 return ImmutableList.of(new OrcType(OrcType.OrcTypeKind.STRING, ImmutableList.of(), ImmutableList.of(), Optional.empty(), Optional.empty(), Optional.empty(), attributes));
             case UUID:
             case FIXED: