currently, they're made by creating a one-line job, but we want to
reduce task/csv file noise so we're moving them to persist in the
same vein as API usage. However, we can't just call through to that
since there are some differences:
* no api keys
* tighter control over API format
* no scheduling
* no client references
etc.
So, re-using as much of the v2 validation stuff as possible, I've
created this file that just does basic validation, and then calls
through to persist_notification and schedules a task. Woo.