Runs a (potentially arbitrary) SQL statement. The command is supposed to perform actions
on tables in the current
OUTPUT repository (the command is executed with the
being the default one) and isn't supposed to read/change data in/from other schemas.
The image hash produced by this command is a combination of the current
OUTPUT hash and the hash of the SQL statement. Note that non-deterministic
SQL statements, for example
SELECT random(), will produce the same hash given the same inputs.