[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-common/src/test/java/org/apache/hudi/common/functional/TestHoodieLogFormat.java

@@ -2038,7 +2038,7 @@ public class TestHoodieLogFormat extends HoodieCommonTestHarness {
    * Utility to convert the given iterator to a List.
    */
   private static List<IndexedRecord> getRecords(HoodieDataBlock dataBlock) {
-    ClosableIterator<IndexedRecord> itr = dataBlock.getRecordItr();
+    ClosableIterator<IndexedRecord> itr = dataBlock.getRecordIterator();
 
     List<IndexedRecord> elements = new ArrayList<>();
     itr.forEachRemaining(elements::add);