feature request: ability to split by TIME_FORMAT druid sql equivalent.

[danielhdz56]

Hello,

I currently use timePart('HOUR_OF_DAY') to group by across many years.
I would also like to be able to group by hour of day and year across many years.
For example:

select SUM("value") as val, TIME_FORMAT(__time, 'YYYY-HH') AS "date" FROM "datasource" GROUP BY TIME_FORMAT(__time, 'YYYY-HH')

The above works in the druid sql console. I would love to have this ability in plywood as well.