Simplify the collection of roots in this repo

[Preston12321]

• Our Sunlight logs are able to pull publicly-trusted root CAs from CCADB directly. Stop tracking them in this repository.
• We've got a ton of crusty roots that aren't needed by modern certificate submitters. Delete them out of the common collection.
• Holding the roots our CT logs trust is the primary purpose of this repo. Hoist those collections out of tooling/ into the root of the repository. Also, generalize sapling/twig/etc collections to a single testing collection.