feat: add initial-default key

Author: suhwan-cheon

flink-cdc-connect/flink-cdc-pipeline-connectors/flink-cdc-pipeline-connector-iceberg/src/main/java/org/apache/flink/cdc/connectors/iceberg/sink/IcebergMetadataApplier.java

@@ -237,12 +237,13 @@ private void applyAddColumnEventWithPosition(Table table, AddColumnEvent event)
                         FlinkSchemaUtil.convert(
                                 DataTypeUtils.toFlinkDataType(addColumn.getType())
                                         .getLogicalType());
-                updateSchema.addColumn(columnName, icebergType, columnComment);
                 Literal<?> defaultValue =
                         IcebergTypeUtils.parseDefaultValue(
                                 addColumn.getDefaultValueExpression(), addColumn.getType());
                 if (defaultValue != null) {
-                    updateSchema.updateColumnDefault(columnName, defaultValue);
+                    updateSchema.addColumn(columnName, icebergType, columnComment, defaultValue);
+                } else {
+                    updateSchema.addColumn(columnName, icebergType, columnComment);
                 }
                 switch (columnWithPosition.getPosition()) {
                     case FIRST: