fixes https://github.com/TryGhost/Toolbox/issues/370
- we no longer need `bthreads` because we can use native
`worker_threads` now we don't have to support Node 10 any longer
- this allows us to clean up a dependency and stick with native
libraries
- the referenced node-sqlite3 issue should be fixed (or at least, we now
maintain it so we can fix it if not)
refs https://github.com/TryGhost/Toolbox/issues/357
- Job persisted in the database need to track job's execution status such as completion, failure, execution start and end times. This changeset allows to hook into job/bree lifecycle to track job's progress.
- NOTE: only supports "offloaded" jobs at the moment. Support for "inline" jobs will be added once there's a clear usecase for it.
- The "started" status and "started_at" timestamp are assigned to a job at the moment when the worker thread is created inside of bree
- The "finished" status and "finished_at" timestamp are assigned to a job when a "done" event is passed from the job script (NOTE: using process.exit(0) will not trigger the "finished" state")
- The "failed" status is assigned when the job execution is interrupted with an error
refs https://github.com/TryGhost/Ghost/issues/12496
- `workerMessageHandler` option allows for custom worker message handling and allows to eliminate a need for loggers of any type inside of jobs.
- removing loggers from jobs solves file hanle leak which used to cause Ghost process to crash (see referenced issue)
