Add DuckDB (Parquet) results

[Mytherin]

This PR adds results for DuckDB running over Parquet files. I have used the same Parquet files as clickhouse-local.

Note that there are some issues with the Parquet file metadata (see #18). Specifically the VARCHAR, DATE and TIMESTAMP columns are not correctly marked as such. I have added the following work-around to the view to get this to work:

CREATE VIEW hits AS
SELECT *
	REPLACE
	(epoch_ms(EventTime * 1000) AS EventTime,
	 DATE '1970-01-01' + INTERVAL (EventDate) DAYS AS EventDate)
FROM read_parquet('hits_*.parquet', binary_as_string=True);

Essentially constructing the correct TIMESTAMP and DATE fields from the Parquet.

[alexey-milovidov]

Thank you! It appeared faster than clickhouse-local.