Introduce "Quarterly" Option for JO Schedules

I walked in to this one expecting that it was already a thing. We can currently set up daily / weekly / monthly schedules for JO. The missing piece of the puzzle which is common enough in business that there are question threads on it already is: quarterly.

Workarounds range from simple enough (adjust the source schedule, but will result in inflated failed participant counts) to “things I would never hope to do in production” (creating a custom calendar object for joins and flagging in query logic). It would be fantastic is we could add a standard Quarterly option to the OOTB scheduler mechanism.

Even better: allow us to use cron expressions for this. Being able to schedule a JO Program for the 1st Monday of every 3rd month SOUNDS like a wild ask, but consider: webinars, feature digests, newsletters, etc. It’s actually not that unusual for businesses to want to control scheduling in a way that cron expressions are uniquely fit for.

This would also massively cut down on the number of one-time “Q2 / Q3 / Q4” Programs we find hanging out in an aged instance we’ve inherited.