[FLINK-28255] Add extraFiles to DataFileMeta

[JingsongLi]

See FLINK-28244

class DataFileMeta {
   String fileName;
   .....
   // store the name of extra files, extra files including changelog_file,
  // primary_key_index_file,secondary_index_file, and etc...
   List<String> extraFiles;
}

Extra files can help us for many uses, including index files, changelog files and etc...

[JingsongLi]

We don't need this cache now, we can just use pathFactory.bucketPath.
Although it will convert the partition to string once at a time. The cost is not large.