Add more statistics to the query results

Now, the query result contains scaned rows, scaned bytes. There are some other statistics can be added like the number of scan files, spark scan time, etc.

It will be useful to add the number of parquet files scaned when querying, especially, the shard by column is configured which will decrease the   number of scaned parquet files to improve query efficency. 

To read more about shard by column with below link.

https://cwiki.apache.org/confluence/display/KYLIN/Improving+query+effeciency+by+set+shard+by+column