[HUDI-1013] Adding Bulk Insert V2 implementation (#1834)

- Adding ability to use native spark row writing for bulk_insert
 - Controlled by `ENABLE_ROW_WRITER_OPT_KEY` datasource write option
 - Introduced KeyGeneratorInterface in hudi-client, moved KeyGenerator back to hudi-spark
 - Simplified the new API additions to just two new methods : getRecordKey(row), getPartitionPath(row)
 - Fixed all built-in key generators with new APIs
 - Made the field position map lazily created upon the first call to row based apis
 - Implemented native row based key generators for CustomKeyGenerator
 - Fixed all the tests, with these new APIs

Co-authored-by: Balaji Varadarajan <varadarb@uber.com>
Co-authored-by: Vinoth Chandar <vinoth@apache.org>

hudi-common/src/main/java/org/apache/hudi/common/model/HoodieRecord.java

@@ -18,12 +18,16 @@
 
 package org.apache.hudi.common.model;
 
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import org.apache.hudi.common.util.CollectionUtils;
 import org.apache.hudi.common.util.Option;
 
 import java.io.Serializable;
 import java.util.List;
 import java.util.Objects;
+import org.apache.hudi.common.util.collection.Pair;
 
 /**
  * A Single Record managed by Hoodie.
@@ -40,6 +44,10 @@ public class HoodieRecord<T extends HoodieRecordPayload> implements Serializable
       CollectionUtils.createImmutableList(COMMIT_TIME_METADATA_FIELD, COMMIT_SEQNO_METADATA_FIELD,
           RECORD_KEY_METADATA_FIELD, PARTITION_PATH_METADATA_FIELD, FILENAME_METADATA_FIELD);
 
+  public static final Map<String, Integer> HOODIE_META_COLUMNS_NAME_TO_POS =
+      IntStream.range(0, HOODIE_META_COLUMNS.size()).mapToObj(idx -> Pair.of(HOODIE_META_COLUMNS.get(idx), idx))
+          .collect(Collectors.toMap(Pair::getKey, Pair::getValue));
+
   /**
    * Identifies the record across the table.
    */