Compare 2 collections in OSO web app

[ryscheng]

What is it?

There are a couple reasons why you might compare 2 collections:

1. Cohort analysis (e.g. RF3 vs RF4)
2. Competitive analysis

Either way, it's useful to see net difference between any 2 collections. Maybe something like /collections/compare/collectionName1/collectionName2, which shows a modified CollectionPage. In this case, collectionName1 would be the baseline and we show green/red deltas on each key metric card that reflects the difference between the 2. We can also plot time series metrics side by side.