Ref T6238. I'm building the instance management application now, but not putting it in the upstream -- I think the only use case for it is to build SAAS. If someone comes up with a use case (maybe a college course that wants to create an instance per-class or something?) we could open it up eventually, but it seems cleaner to keep it out of the upstream until we have such a use case.

I need to add schema patches. Make it easier for a subclass to just "add all the patches in this directory", like "autopatches/" works.

• Ran bin/storage status, saw all normal patches still valid.
• In some future diff, the instances application will use this to apply patches.