Auto-generating of "Candidates for Data Pool" list for Pool editors

[ethanmiller4]

Currently, when someone adds a new listing to the find.coop data set (either directly or via a curated view such as maine.find.coop), the editors of various Data Pools have no way of knowing this without going to find.coop and digging around. We should have a feature that appears for editors of a given data pool that aggregates "candidates"--listings that aren't currently in their data pool that they might want to approve. This would include: (a) listings that someone tried to add to the specific pool, and that are awaiting approval (these should be marked as such); and (b) listings that have been added via other views/sites/pools that might be relevant based on a set of specific filters (for maine.find.coop, for example, all listings with locations in Maine).