[HUDI-2488][HUDI-3175] Implement async metadata indexing (#4693)

- Add a new action called INDEX, whose state transition is described in the RFC.
- Changes in timeline to support the new action.
- Add an index planner in ScheduleIndexActionExecutor.
- Add index plan executor in RunIndexActionExecutor.
- Add 3 APIs in HoodieTableMetadataWriter; a) scheduleIndex: will generate an index plan based on latest completed instant, initialize file groups and add a requested INDEX instant, b) index: executes the index plan and also takes care of writes that happened after indexing was requested, c) dropIndex: will drop index by removing the given metadata partition.
- Add 2 new table configs to serve as the source of truth for inflight and completed indexes.
- Support upgrade/downgrade taking care of the newly added configs.
- Add tool to trigger indexing in HoodieIndexer.
- Handle corner cases related to partial failures.
- Abort gracefully after deleting partition and instant.
- Handle other actions in timeline to consider before catching up

hudi-client/hudi-flink-client/src/main/java/org/apache/hudi/table/HoodieFlinkCopyOnWriteTable.java

@@ -22,6 +22,8 @@ import org.apache.hudi.avro.model.HoodieCleanMetadata;
 import org.apache.hudi.avro.model.HoodieCleanerPlan;
 import org.apache.hudi.avro.model.HoodieClusteringPlan;
 import org.apache.hudi.avro.model.HoodieCompactionPlan;
+import org.apache.hudi.avro.model.HoodieIndexCommitMetadata;
+import org.apache.hudi.avro.model.HoodieIndexPlan;
 import org.apache.hudi.avro.model.HoodieRestoreMetadata;
 import org.apache.hudi.avro.model.HoodieRestorePlan;
 import org.apache.hudi.avro.model.HoodieRollbackMetadata;
@@ -48,6 +50,7 @@ import org.apache.hudi.io.HoodieSortedMergeHandle;
 import org.apache.hudi.io.HoodieWriteHandle;
 import org.apache.hudi.keygen.BaseKeyGenerator;
 import org.apache.hudi.keygen.factory.HoodieAvroKeyGeneratorFactory;
+import org.apache.hudi.metadata.MetadataPartitionType;
 import org.apache.hudi.table.action.HoodieWriteMetadata;
 import org.apache.hudi.table.action.bootstrap.HoodieBootstrapWriteMetadata;
 import org.apache.hudi.table.action.clean.CleanActionExecutor;
@@ -330,6 +333,16 @@ public class HoodieFlinkCopyOnWriteTable<T extends HoodieRecordPayload>
     return new CopyOnWriteRollbackActionExecutor(context, config, this, rollbackInstantTime, commitInstant, deleteInstants, skipLocking).execute();
   }
 
+  @Override
+  public Option<HoodieIndexPlan> scheduleIndexing(HoodieEngineContext context, String indexInstantTime, List<MetadataPartitionType> partitionsToIndex) {
+    throw new HoodieNotSupportedException("Metadata indexing is not supported for a Flink table yet.");
+  }
+
+  @Override
+  public Option<HoodieIndexCommitMetadata> index(HoodieEngineContext context, String indexInstantTime) {
+    throw new HoodieNotSupportedException("Metadata indexing is not supported for a Flink table yet.");
+  }
+
   @Override
   public HoodieSavepointMetadata savepoint(HoodieEngineContext context, String instantToSavepoint, String user, String comment) {
     throw new HoodieNotSupportedException("Savepoint is not supported yet");