Cancel a running console query

Runs one or more statements (split on `;` outside literals, comments and dollar quotes; MySQL `DELIMITER` lines are honoured) in order on one session, stopping at the first failure. Reads run as the database's read-only role; a script with any write runs as its read-write role and requires database:write (checked before anything runs). A failing first statement is returned as an error; a later failure returns the earlier results plus `error`. Pass `query_id` (a UUID you generate) to be able to cancel the run.