This generally looks good, but we should make two changes which aren't entirely straightforward:

• Let's wait for D8387 and use that style (array of flags instead of string).
• I don't want to add new .arcconfig options, since .arclint will obsolete them. However, .arclint is in a weird limbo right now and we don't have a solid technical approach for deprecating .arcconfig options or letting you use older linters easily without introducing them. Let me come up with a more concrete approach here.

I'll follow up with specific guidance once some of the ambiguity here clears up. Ideally, I'd like to get .arclint pushed forward enough to start recommending it, but I'm not sure how my priorities will line up.