Use a variable to add (or auto add) time range in druid SQL

[raakasf]

Currently, when using druid SQL users have to add the time window (see below) to the WHERE clause.

AND __time >= MILLIS_TO_TIMESTAMP(${__from}) AND __time <= MILLIS_TO_TIMESTAMP(${__to})

It would be nice if one could use $timefilter or something similar to what the postgres plugin provides (see https://grafana.com/docs/grafana/latest/variables/variable-types/global-variables/#timefilter-or-__timefilter).

It would be awesome if we could have some druid SQL parser (Druid Query Toolkit provides functions like addToWhere) to automatically add the above time window to users SQL.