Issue description

With bank sync support via SimpleFIN or LunchFlow, we need a way to automatically sync on a periodic basis (likely just daily).

The easiest way to do this is by adding onto the existing cron job schedule.yml:

  cron: "0 5 * * *"
  class: "SyncJob"
  queue: "scheduled"
  description: "Executes account syncing"

Currently the SyncJob cannot be invoked this way -- it needs to be modified to handle being initialized with nothing (which should be straight forward, at least how much I've investigated so far).

Alternatively, we could add a separate class for it, but it doesn't seem distinct enough to do that (I don't have a strong opinion on that, though).

The sync providers likely have some guidelines on acceptable query patterns (e.g. don't sync more than once per day), would be good to include links to that guidance if it exists.