appendRowGroup will loose pageIndex

Currently, 
org.apache.parquet.hadoop.ParquetFileWriter#appendFile(org.apache.parquet.io.InputFile) uses appendRowGroup method to concate parquet row group. However, appendRowGroup method **looses** column index.
```java

// code placeholder
  public void appendRowGroup(SeekableInputStream from, BlockMetaData rowGroup,
                             boolean dropColumns) throws IOException {
....
    // TODO: column/offset indexes are not copied
      // (it would require seeking to the end of the file for each row groups)
      currentColumnIndexes.add(null);
      currentOffsetIndexes.add(null);
}
```
 

Look forward to functionality that support append with page index.

**Reporter**: [GANHONGNAN](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=NathanKan)

_{**Note**: *This issue was originally created as [PARQUET-2340](https://issues.apache.org/jira/browse/PARQUET-2340). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}