This module implements a simple `queue.job` runner using `ir.cron`
triggers.

It's meant to be used on environments where the regular job runner can't
be run, like on Odoo.sh.

Unlike the regular job runner, where jobs are dispatched to the
HttpWorkers, jobs are processed on the CronWorker threads by the job
runner crons. This is a design decision because:

- Odoo.sh puts HttpWorkers to sleep when there's no network activity
- HttpWorkers are meant for traffic. Users shouldn't pay the price of
  background tasks.

For now, it only implements the most basic features of the `queue_job`
runner, notably no channel capacity nor priorities. Please check the
ROADMAP for further details.
