[HUDI-3760] Adding capability to fetch Metadata Records by prefix (#5208)

- Adding capability to fetch Metadata Records by key prefix so that Data Skipping could fetch only Column Stats 
- Index records pertaining to the columns being queried by, instead of reading out whole Index.
- Fixed usages of HFileScanner in HFileReader. few code paths uses cached scanner if available. Other code paths uses its own HFileScanner w/ positional read. 

Brief change log
- Rebasing ColumnStatsIndexSupport to rely on HoodieBackedTableMetadata in lieu of reading t/h Spark DS
- Adding methods enabling key-prefix lookups to HoodiFileReader, HoodieHFileReader
- Wiring key-prefix lookup t/h LogRecordScanner impls
- Cleaning up HoodieHFileReader impl

Co-authored-by: sivabalan <n.siva.b@gmail.com>
Co-authored-by: Sagar Sumit <sagarsumit09@gmail.com>

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/client/HoodieTimelineArchiver.java

@@ -339,7 +339,7 @@ public class HoodieTimelineArchiver<T extends HoodieAvroPayload, I, K, O> {
           // Read the avro blocks
           while (reader.hasNext()) {
             HoodieAvroDataBlock blk = (HoodieAvroDataBlock) reader.next();
-            blk.getRecordItr().forEachRemaining(records::add);
+            blk.getRecordIterator().forEachRemaining(records::add);
             if (records.size() >= this.config.getCommitArchivalBatchSize()) {
               writeToFile(wrapperSchema, records);
             }

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/storage/HoodieHFileWriter.java

@@ -107,7 +107,7 @@ public class HoodieHFileWriter<T extends HoodieRecordPayload, R extends IndexedR
         .withFileContext(context)
         .create();
 
-    writer.appendFileInfo(HoodieHFileReader.KEY_SCHEMA.getBytes(), schema.toString().getBytes());
+    writer.appendFileInfo(HoodieHFileReader.SCHEMA_KEY.getBytes(), schema.toString().getBytes());
   }
 
   @Override