Refactor FileSystemBackedTableMetadata and related classes to support getColumnStats directly

The api {{getColumnStats}} is not supported in FileSystemBackedTableMetadata:
{code:java}
@Override
public Map, HoodieMetadataColumnStats> getColumnStats(final List> partitionNameFileNameList, final String columnName)
throws HoodieMetadataException {
throw new HoodieMetadataException("Unsupported operation: getColumnsStats!");
} {code}
It's better to support column stats without metadata table from FileSystemBackedTableMetadata as well to unify the logic around col stats and reduce the special-cased logic for col stats between metadata table vs file system backed metadata.

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-3532
- Type: Improvement
- Epic: https://issues.apache.org/jira/browse/HUDI-6243

---

## Comments

25/Apr/22 12:35;xushiyan;We may not need to do this. It may not be a good practice to allow this API via FS listing.;;;

Start by locating FileSystemBackedTableMetadata and its getColumnStats implementation, then trace the related metadata classes and callers that special-case column statistics. Confirm whether filesystem listing should support this API, and consider the issue complete only when the agreed behavior is implemented consistently and covered by the relevant tests.

Written by the indexing model from the issue text.