TileRequest: Add Datasette tiles

[breck7]

Datasette has some great datasettes. https://github.com/simonw/datasette

Also might make more sense to use that for this: http://datasets.ohayo.computer/

[alexey-milovidov]

There is a good list of real-world datasets of moderate size: https://clickhouse.com/docs/en/getting-started/example-datasets